Hidden Mechanic

^{Q: What is a Hidden Mechanic?}A: Hidden Mechanic is something that adds quality of life or increased success for the player — a sort of shortcut or advantage, that simply isn't hinted at in any way and is left for players to discover for themselves.

^{— Topic Described Here}

It's natural, when designing a video game, to ensure that the player fully understands the Game Mechanics that make the game work. Developer's Foresight failure tends to result in endless frustration. Many tutorials, however cumbersome, have been created to avoid this. At the least, when a new mechanic appears it tends to correspond with a tooltext explaining how it works.

Yet sometimes, developers go the opposite direction and include a mechanic that is not alluded to anywhere in the game. Even after a player discovers it, it won't be mentioned, but will still impact the gameplay and the ultimate result. It won't be needed to complete the game, but knowing about it will probably help. If the player is lucky, there might be hints about it All There in the Manual, but often even this resource is barren.

There are a couple of reasons this might be done. The most common is to create a kind of bonus content for hardcore players: those who play the game with the most thorough and exhaustive of approaches will discover the mechanic and be able to exploit it. Another reason might be to create a kind of soft debug mode, such that a developer or other person in the know can breeze through parts of the game in order to more quickly reach other content. Discovering this can allow a player to engage in Dynamic Difficulty without suffering Easy-Mode Mockery.

These mechanics are not limited to just abilities the player has, but can also include the game's internal systems, with common features including making the player's final sliver of health last much longer than it should and/or making enemies less accurate against mortally wounded players to create more dramatic comebacks from almost certain death, altering RNG so that the player won't get too many unlucky events in a row, giving the computer more or abilities to compensate for its reduced intelligence, or dynamically altering the difficulty to try to keep the challenge level enjoyable for the player.

Finding it is much like an Easter Egg, only it goes far beyond that most of the time. To maintain the comparison, it is like finding an omelet recipe or an instant omelet cooking device... yumm!

Where Guide Dang It! comes into play is situations where some game feature is needed to progress effectively, but is not well communicated to the player, even beyond the scope of what developers might have thought to be an easily made connection that seemed intuitive because of their aversion to Unexpectedly Realistic Gameplay.

This can overlap with Cheat Code, as many cheats are not mentioned in the game materials at all, their purpose being for players to unlock them or even purchase them from the company separately and provide a means of ease of use, however it may lead to No Fair Cheating if the mechanic in question is so well hidden that Developer's Foresight accounted for through a particularly noteworthy Genius Programming.

See also Good Bad Bugs, where programming oversights result in mechanics, or rather glitch exploit, that players can find and use for their benefit. Because of that, it may lead to Ascended Glitch, where a mechanic originating from a glitch becomes an actual (even integral) feature, yet the tutorial of the game still doesn't bother to explain it. Of course, there is also Meta Game where new strategies are uncovered as people keep playing the game.

Might lead to, or be the grain of truth behind, an Urban Legend of Zelda, because a hint of a mechanic existing in the game might be there but developers might have cut it. Conversely, the mechanic was planned and implemented but not documented.

---

Examples^:Mechanics

Action-Adventure Games

• NiGHTS into Dreams… has the "A-Life" (for "artificial life") system, a surprisingly involved simulation governing the behavior of NPC Nightopians in each level. Across multiple playthroughs of a level, Nightopians (or Pians for short) will hatch from eggs, play amongst themselves, and "disappear" after they grow old enough. The player's actions in a level can influence their growth: hatching eggs and defeating Nightmarens will make the Pians happy and cause their population to grow while attacking Pians will make the survivors fearful of you. Furthermore, leftover orbs from any Nightmarens you defeat can collide with a Pian and make them breed a hybrid, called a Mepian—and if two Mepians breed, there's a random chance their offspring can be a rare King Pian, who will build a castle in the background of that level. None of this has any bearing on actually beating the game, so it's never explained to the player.
• Ōkami: Normally, after Amaterasu learns the standard version of a Brush technique, she can later undertake a sidequest to unlock a variant of that technique, being either a stronger version usable during battle or a uniquely distinct version that serves a different function. However, the variant of the Blizzard technique (Icestorm) is unique in that it's made secretly available after Amaterasu learns Blizzard itself, not requiring any sidequest but also not being alluded to or mentioned in any capacity.
• The Legend of Zelda: The Minish Cap: At one point, you have to scoop up water with a bottle and pour it on a seed to make it grow. The game gives you no indication that this is possible.
• The Legend of Zelda: Twilight Princess: A quick slash after a roll results in Link doing a roll stab. Also pressing A to sheathe your sword shortly after defeating an enemy will result in Link doing a complex and stylish sword play animation before sheathing it.

Action-RPG

• Kingdom Hearts:
  • In most games, when the EXP Zero ability is activated, a secret "damage floor" mechanic kicks in where all of Sora's attacks will deal a fixed amount of minimum damage if his Strength and/or Magic stats are sufficiently below the world's Combat Level. This makes your actual battle stats irrelevant and allows the game to proceed without Sora being reduced to inflicting Scratch Damage.
  • In Kingdom Hearts, having EXP Zero on additionally gives Sora a hidden "one-shot protection" effect, where if he is attacked while at full HP, he cannot be killed even if the attack would normally kill him.
  • Kingdom Hearts II: The Anti-Form is randomly activated whenever the player uses Drive Forms. However this is triggered by a hidden "Anti-Point" counter which adds one point whenever the player uses Valour, Wisdom, Master, or Limit Forms but reduces it by 10 whenever Final Form is used, and resets entirely whenever a new Drive form is obtained. If Sora has the Two Become One keyblade equipped, its special Ability Light & Dark will make it so that any attempt to use a Drive Form either activates Anti or Final Forms, which is the closest the player will get to being able to use Anti-Form willfully.
• Science Girls!: The Relationship Values that determine which Final Boss happens, are hidden from the player.

Fighting Games

• Bloody Battle has a hidden mechanic in the form of consuming 5 Joy (a healing item) in life will lead you to become a mutant in death. Nowhere does it mention that this'll happen in the item description. On a more minor scale, the bleeding and emesis effects along with all the traumas are simply named but never explained resulting in players having to find them out the hard way.
• Mortal Kombat 9 has a mechanic hidden in what appears to be an innocuous Easter Egg called the "Toasty Boost". The game features the classic "Toasty!" easter egg originated from Mortal Kombat II (where occasionally upon landing a vicious uppercut, a still of sound designer Dan Forden will pop up in the corner to say "Toasty!"), but a further secret is that once it appears, being the first player to input a hidden combination of buttons will result in what the text calls a "Toasty Boost" that will immediately max out your super meter. Due to the incredible specificity of this mechanic (each playable character had a different, specific input code), fans didn't realize this mechanic existed until years after the game came out, and when it was discovered, this ended up significantly affecting the competitive/tournament metagame, with some players making strategies based around the mad dash to trigger the Easter Egg and claim the "Toasty Boost" for a massive advantage.
• Super Smash Bros.:
  • An ability officially known as "smooth landing" in Super Smash Bros. 64 and more commonly known in as "Z-cancelling" (in 64) or "L-cancelling" (in Melee) is a mechanic not mentioned in the game itself (but mentioned by the 64 official website) that allows you to reduce the landing lag induced by standard aerial attacks by pressing the Z button (in 64) or L, R, or Z buttons (in Melee) with a certain timing right before you hit the ground, which will cause your character to do their normal landing animation instead of their slower post-attack landing animation. This was one of several mechanics removed in Brawl as Masahiro Sakurai disliked that it widened the gap between casual and competitive players.
  • In Super Smash Bros. Melee and Brawl, there is a technique known as "meteor canceling", which allows you to negate the knockback of a meteor smash (any attack with a sufficient knockback value that sends downwards within a certain angle range) by inputting a jump after being hit. This makes meteor smashes much worse at scoring kills compared to spikes (attacks that send downward but outside of the meteor smash angle) since the opponent can simply jump out of them if they react fast enough. Understandably, this was removed from Super Smash Bros. for Nintendo 3DS and Wii U onwards.
  • There is a concept known as "glancing blows", which is more commonly known among the Melee community as "phantom hits". A glancing blow occurs if an attack's hitbox connects with an opponent's hurtbox with exactly a 0.01 distance unit overlap. In Melee, a glancing blow deals half damage to the opponent without knockback or flinching and causes hitlag for the opponent. From Brawl onwards, glancing blows do not deal damage nor do they inflict hitlag or hitstun, making them functionally redundant.
  • An extremely difficult and obscure technique in Melee exists known by fans as "V-cancelling", which is akin to a form of teching for aerial attacks. If the player presses L or R within 1 to 2 frames of being hit by an attack while airborne and is not in hitstun, attacking, or floating (in Peach's case) and has not pressed the L/R button in the last 40 frames, they will perform a V-cancel, which reduces the knockback of the resulting attack by 5%. This is never mentioned in-game and is so arcane that it was not discovered until over a decade from the game's release.
  • Possibly the single most infuriating mechanic ever added to the series was itself never explicitly mentioned by the game^note The game does keep track of how many times it occurs as a stat, but does not explain what it is or why it happens, which is Brawl's tripping mechanic, otherwise officially known as "prat falling". The mechanic is that whenever you input a dash command or turnaround dash, there is a base 1% chance (1.25% for turnarounds) that you will fail to dash and instead completely tumble over and fall on the stage prone, making you extremely vulnerable to your opponent's attacks until you get up. This makes aggressive approaches and constant ground movement very risky, as on the off chance that you trip you are basically easy pickings for your opponent and can at best be punished and at worst lead to death. This mechanic did not survive outside of Brawl and was removed in for Nintendo 3DS and Wii U.
  • Super Smash Bros. Brawl: The Pokémon Trainer has a unique debilitating mechanic called Stamina, which is not alluded to anywhere in the game. The gist of it is that every Pokémon has a hidden Stamina gauge, starting from 100, and ticks down by 1 point every 2 seconds while the Pokémon is deployed. When a Pokémon's Stamina drops below 30, that Pokémon starts receiving a gradual decrease in damage and knockback output, up to a 30% decrease in overall effectiveness, and is indicated by the Pokémon switching to a "fatigued" stance. Stamina can be replenished by switching out the active Pokémon, which will gradually heal Stamina, or upon being KO'd, which will immediately heal up to 70% Stamina for the active Pokémon. Predictably, being forced to periodically switch Pokémon made the Pokémon Trainer much worse, and thus the mechanic was removed completely when they were brought back for Super Smash Bros. Ultimate.

First Person Shooter Games

• Bioshock: In any ambush, enemies will always miss their first shot so that the player won't be killed before getting the chance to react.
• The Borderlands series:
  • Legendary Weapons usually come with some special effects and most are only discoverable in-game by experimentation, such as Borderlands 2's Sand Hawk fires in a bird-shaped pattern when zoomed in, and its only unique information being the Tenuously Connected Flavor Text of "In. Not unlike Errol.", when combined with its name, is a Shout-Out to The Sea Hawk and Errol Flynn.
  • Borderlands: Eridian Blasters come in multiple forms, differentiated by the second word in the gun's name, and they all affect how the projectiles work, but the only information available for each gun when acquired, is the Tenuously Connected Flavor Text of "Pew Pew Pew!" and the damage, accuracy, and fire rate.
  • "Burst fire when zoomed" has a different number of possible rounds used in each burst firing and appears in Borderlands 2 and Borderlands: The Pre-Sequel!. For example: 2's Sand Hawk uses 24 rounds each burst and Pre-Sequel's Major Tom uses up 10 rounds each burst.
• Counter-Strike never bothers with explaining the ammunition sharing mechanic. Certain guns use the same ammunition and it's made quite realistically — i.e. only guns using the same caliber share ammo. The problem is, certain SMGs^note primary weapon share ammo with handguns^note secondary weapon so if you happen to have such combination and deplete your ammo pool with one gun, you have no ammo left for the other. On the other hand, ammo is only dropped if you're killed and not if you manually drop your gun. Which means, you can stockpile on ammo just by picking up several guns from dead enemies or teammates and then dropping them. On top of that, acquiring ammo of different caliber does not discard your previous. Basically you may only carry two guns at a time but can be a walking ammunition storage without having a slightest hint.
• Doom has strafe-running, where moving forward and strafing to the right at the same time gives a speed boost, along with other features that allowed fast movement. The developer didn't consider them intentional and took efforts to reduce them in their next game engine.
• Halo: Most games feature a mechanic where dying too many times will cause the game to give you an extra checkpoint so you don't have to replay the entire segment you're having trouble with.
• The Quake series have strafe jumping (and an advanced form known as bunny hopping), which gave a significant advantage to speed boosts in multiplayer deathmatch. There was an attempt to remove this in Quake III: Arena, but was unsuccessful as it would make running awkward.
• Team Fortress 2 has mechanics in many weapons that go unmentioned. For example, the Backburner has no random crits, the Pomson has only 4 shots instead of 6, and the Disciplinary Action has 70% more range.
• Unreal Tournament has several:
  • The Lift Jump. Jumping before a platform reaches its highest point propels the player, allowing them to use shortcuts when navigating through the maps.
  • The Impact Hammer's "deviation"/"deflection" attack. The secondary fire allows players to deflect or deviate enemy projectiles before they reach them, the key difference between the two being the timing. The Impact Hammer's primary fire can also be used to send the player's own Translocator disc farther away than simply shooting the disc from the Translocator itself.
  • Neither Unreal Tournament 2003 nor Unreal Tournament 2004 bother to explain how combo movement options work in their tutorials. There are certain "frames" of the player's movement where an additional move can be inputted, this is basically how Double Jump and Wall Jump works. What the game doesn't tell you is that you can combo Dodges with Jumps, leading to the fast-traversing Dodge Jump, or that you can increase the distance length or height of your Wall Jump by jumping at certain points of the Wall Jump. If you wall-jump and jump again, you gain extra distance, however if you jump and then wall-jump, you'll be able to reach higher heights, which in certain maps can grant you either shortcuts or secret items. Dodge-jumping is, in fact, the preferred travel method in Onslaught maps when you cannot get into a vehicle.

Hack and Slash Games

• Devil May Cry 2: If the player is at critical health and activates Devil Trigger while playing as Dante, they'll end up activating the Sin Devil Trigger instead of their regular one. The Sin Devil Trigger is far more powerful, with several moves that allow you to shred enemies and bosses alike whenever you use this form.
• Inverted in Hellblade: Senua's Sacrifice, which has a fake mechanic: the hidden part here being that the mechanic stated in the game is not actually in force. Early on, the player is told that there's a Permadeath mechanic if Senua dies enough times to let the rot on her body reach her head. In fact, this will not occur no matter how many deaths ensue. This lie is meant to give the player a similar level of anxiety about Senua's death that she feels herself.
• Hours (2020) does not bother to explain the starting menu to players, simply prompting them to to click the buttons to find out. This has resulted in players not even knowing that there were different modes until after a bit of playing, nor that there was a whole second page with different options than the first, to the point the second page has actually been called a secret despite being one click of a visible button away.
• Hyrule Warriors: Warriors' defense increases with their level, but the defense stat isn't shown in game.
• Hyrule Warriors: Age of Calamity: While strength increases with the warriors' level, the strength stat isn't displayed except for the weapons' stats.
• No More Heroes 2: Desperate Struggle: When Travis is about to fall down to his death after having all of his HP depleted, he can repeatedly shake the Wiimote (or Joy-Cons in the Switch version) so he recovers a small amount of health and continue fighting. This works up to four times, and it's great for difficult boss fights (the only times it doesn't work are when the last attack received is One-Hit Kill, like the wide-area Kill Sat command from Captain Vladimir or the potential Destination Defenestration effect of Jasper Batt Jr.'s attacks). However, neither the game nor the instructions manual makes any mention of this mechanic.
• Transistor:
  • All There in the Script, in "Transistor/Content/Game/UnitsPlayerUnits.xml", where it reveals information about being a SuperUser, a.k.a "PlayerArchon", which is different from Red's base state, being only able to walk and Kill().
    • It has a set 100 Stamina, a.k.a Turn() Planning Cost, such that even if Red() was using the Breach() passive to get 120 Turn() Planning Cost, she couldn't Kill() twice via the Anti-Frustration Feature that allows use of any Function so long as she had some Turn() Cost remaining since she only had 100, not 120, Stamina as a SuperUser.
    • SuperUser Red needs the least "Stamina" to move per unit of distance, "0.015", compared to the base form even with the Ping() passive, which turned walking cost from "0.05625" to "0.03625" by subtracting 0.02 from the cost.
  • Void() is also a Shrink Ray, but nothing says that, only revealed when used, but it's implied by its icon's arrows.

Metroidvania Games

• The video game based on the Green-Sky Trilogy, Below the Root, had a few surprises, despite it coming out in 1984. NPCs could treat your character very differently, based on selection of avatar, something now taken for granted in role-playing games, but highly unusual for the era. Also, Kindar characters got little nutrition and took a hit to their spirit stat if they ate meat, but Erdlings were not affected. Erdling characters got hit much harder by wissenberries (a narcotic berry that Kindar developed a tolerance for). There was also an Unwinnable by Design mechanic where using the Wand of Befal (machete) against a living being made your spirit stat decrease permanently. There was nothing in the game manual that explained any of this, but if you read the books the game was based on, the mechanics made perfect sense in a form of Fridge Brilliance.
• Bloodstained: Ritual of the Night:
  • Gebel's Glasses immediately refunds all Shards' mana costs' on cast so their casting cost must still be fulfilled first. It's not explained, since the only description is the Flavor Text:
    Hand-me-downs from Johannes. A reminder of days that are now lost.
  • Familiars:
    • Igniculus's unmentioned 50 HP heal when the Expressive Health Bar flashes red, silently also gets a chance to turn into a full healing instead at some point before Rank 4, Grade 5, Level 26.
    • Bloodbringer becomes a wieldable sword at Level 25.
    • Carabosse can indicate the presence of breakable walls after being upgraded enough.
  • Aurora Mode:
    • Increasing the Rank of Rubella increases the healing from casting it, from the starting 55 at Rank 1, Rank 2 is 66, then it's an increase by 12 every time until the Cap of Rank 9, restoring 150 HP. But the game just says for Rubella:
      Rank: Increases the duration.
    • Changing the Conjure Shard that Aurora wields changes her stats. Unlike the base game / Mariam Mode, those stat changes aren't given in a before-and-after listing when the selection is highlighted in the menu.
• Castlevania:
  • Castlevania: Circle of the Moon: Wearing the Bear Ring and using Black Dog + Pluto turns you into a bear, which is only implied by the ring's Flavor Text talking about the "curse of the bear".
  • Castlevania: Aria of Sorrow: Four-legged enemies cannot climb stairs. Only careful observation will tell you this.
  • Konami Man, Twin Bee, and Vic Viper in Castlevania: Portrait of Ruin are gotten as rewards from beating the game on Hard difficulty with a level cap of 1, 25, and 50, respectively: their description only reads "5000 points", but each of them also gives a permanent 50 point bonus to STR, INT and LCK, respectively.
• Hollow Knight:
  • You can equip "charms" to get various powers and benefits, but each charm uses up a number of notches and these are limited. However, it is possible to "overcharm" and equip more charms than you have notches for; doing so causes you to take double damage. The first time you try to equip too many charms, the attempt will be rejected and the extra one will fly back in to your inventory; you have to try overcharming five times before it works.
  • Some charms have hidden effects in addition to the effects explained in the in-game text. For instance, Sharp Shadow is said to make your shadow dash deal damage to enemies, and it does; the text doesn't tell you that it also makes your shadow dash a bit longer than normal.
  • There are many combinations of charms that, if worn together, give a combined effect different from a simple combination of the charms' normal effects. Downplayed in that there is one dialogue line (from Salubra) hinting that charm combinations exist in general, but there is nothing hinting at which charms combine or what their effects are.
• Metroid Dread: Several bosses have hidden interactions with powerups that aren't naturally obtained before fighting them. Morph Ball Bombs allow access to a hidden launcher in the Kraid fight, which will shoot Samus into its belly which can be bombed for massive damage. It's also possible to Flash Shift into Kraid's jaws and fire missiles at his mouth point-blank. You can run against Experiment No. Z-57's wind attack and build up a Shinespark. Properly launching into its head with one will instantly end the fight.
• Metroid: Samus Returns: If you use the Spider Ball to latch onto a wall and then plant a Power Bomb right at that spot, you'll activate a "Super Bomb Jump" that will make you fly across the screen until you hit another surface. While the regular Bomb Jump has been a feature in every game in the series, the Super Bomb Jump is unique to Samus Returns and never gets explicitly explained in the game — though it's admittedly only used for optional item collection (and a secret technique to interrupt one of the Queen Metroid's attacks) rather than anything required to reach the end of the game.
• Pseudoregalia: There are a few moves Sybil can perform that the game doesn't tell you about, such as:
  • Although Sybil will automatically target the nearest enemy when attacking, there's also a Camera Lock-On (activated by holding RB/Right Click) that can further assist in fighting foes, especially the tougher ones. The Map Update added a optional toggle that lets it re-center the camera if no valid targets are nearby.
  • Sybil can throw the Dream Breaker in front of her with LB/Tab. If you then use the Sun Greaves to kick it in midair, it'll home in on the nearest enemy and deal much more damage.
  • After obtaining the Solar Wind upgrade, if you side-flip right when you land from a slide-jump, Sybil will perform an extra-high jump that eclipses any of the other leaps she can otherwise perform in verticality (successful execution of which is indicated by gold afterimages and an audio cue). Bunny-hopping after a slide-jump also lets you retain your gained speed.

Platformer Games

• Blaster Master Zero III intentionally obfuscates the requirement for the Golden Ending by showing you the mechanic that triggers it if successfully fulfilled, but not actually telling you what it means. The "mechanic" is a single gold ring on the pause menu. If Jason spends enough time in super-dimensional space, the gold ring will transform into a pair of gold rings, indicating that the True Ending requirement has been fulfilled and can be activated during the game's finale (which itself is not made 100% clear).
• Bubble Bobble has many special items, all based on various statistical information made during the game. These include blowing bubbles, popping bubbles, jumping, running across the full length of the screen 15 times, and so on.
• Cave Story: The Machine Gun if fully levelled can allow the player to ascend upwards if they point the gun downwards, and as long as they still have ammunition.
• Kirby:
  • Starting in Kirby's Return to Dream Land, the main series games have a form of Mercy Mode where if the player loses to a mid-boss or a world boss, their HP will be reduced and the cool-down between their attacks increases. This applies even if the player gets a Game Over until they either win or quit the game.
  • Kirby: Planet Robobot: During the final boss fight, the player pilots an aircraft, the Robobot Armour in Halberd Mode. One of its functions allows you to use the Sail Wing to do a barrel roll. What the game doesn't tell you is that it can also allow you to deflect some attacks or outright dodge some of them; knowing this is key to making through the True Final Boss fight without ending up in critical condition.
• Lemmings:
  • When clicking on a dense group of lemmings to assign a skill to one lemming in the group, priority is given to lemmings currently performing a skill. Neither the game nor the manual explains this, but right-clicking (on the Amiga version) or option-clicking (on the Mac) will instead assign to an ordinary walking lemming.
  • Between two workers or two walkers, priority will be given to whichever lemming came later out of the trapdoor. The game never requires you to know this, but on some levels, it can help with making precision moves.
• Super Mario Galaxy: In the Cosmic Clone races, you have the ability to do a starting sprint the moment the race begins to gain a speed boost, and if timed well, can help you get a head start against your Cosmic Clone opponents. This is the only time this mechanic is put to good use, but the game itself doesn't allude to it at all, not even in tutorials. You either have to figure it out yourself through experimentation or look up a guide.
• Völgarr the Viking: After rolling, you can jump even if you've rolled off the platform, allowing Volgarr to cross larger distances. Also, shield blocks projectiles even when behind Volgarr's back while he's climbing.

Puzzle Games

• Chip's Challenge: In the Atari Lynx and Steam versions of the game, it is possible to passively move a block while walking past them. This is known as block slapping, and it's useful to move blocks that have fire or bombs underneath (trying to push them directly will lead to Chip touching the fire or bomb, dying instantly); there's no hint in-game that alludes to the existence of this ability, which forces unsuspecting players to guess which blocks have fire and ignore them to use blocks without anything beneath instead, leading to a lot of trial and error. In the Microsoft Windows version, due to how the game is programmed, block slapping isn't possible, which means that the trial and error ensuing from trying to avoid the blocks with fire is inevitable.
• Motherload has a number of game mechanics which are not explained to the player. The player must learn them by experience, observation, and experimentation.
  • Earthquakes
    • Every time an earthquake occurs, new valuable items (ores and artifacts) will appear underground on the left border of the screen. If a player has already collected all of the valuable ores and artifacts in a given area, this will allow them to pick up the new items for more cash. The player isn't told about this.
    • Earthquakes can only occur immediately after you leave a building on the surface. This prevents the player from being trapped underground by one. The player isn't told about this.
  • It is only possible to detonate dynamite and plastic explosives when your machine is on the ground, not when flying through the air. The player isn't told about this.
  • Your depth below the surface has several effects on play.
    • The lower your machine is underground, the slower the speed at which you can drill through the ground. The player isn't told about this.
    • The deeper you are, the more the ore you're carrying weighs. A player can have a full load of ore down deep and barely be able to move. If they teleport up to the surface, they can suddenly move quickly without getting rid of any ore they're carrying. The player isn't told about this.
    • Certain minerals will only start to appear at specific depths. The more valuable the mineral, the deeper it will be before it appears. Certain blockages and deadly hazards start occurring at specific depths, the same as minerals. You can start finding valuable artifacts below 1,000 feet. The player isn't told about this.
    • The farther down you are, the more damage you take from running into lava or gas pockets, and the more common they will become. The player isn't told about this.
  • Fighting Mr. Natas and Satan
    • Each time you defeat them, the next time you fight them they have more Hit Points and do more damage to you. The player isn't told about this.
    • You cannot check your inventory while fighting them. This means you can't check on how many hull repair nanobots and plastic explosives you have left. The player isn't told about this.
    • If you fly out of the bottom area where you fight them and go high enough, the encounter will reset to the beginning and all of the damage you inflicted on them will be healed. The player isn't told about this.
    • Sometimes your hull point display will become white, preventing you from knowing how many hull points you have left. The next time you take damage, the display will return to normal. The player isn't told about this.
• Tetris:
  • Across Tetris games descended from Sega's 1988 arcade version, the game processes sideways movement and piece rotations before gravity. This isn't really noteworthy at lower gravity, but when the game starts to drop pieces at a rate of one grid cell every frame, the player can take advantage of this to "jump" pieces across gaps, in a technique known within the community as a "synchro".
  • Tetris: The Grand Master, all three arcade installments: If the player starts to make a formation of blocks such that the holes form a ">" (greater-than sign), and completes at least the first horizontal half of the formation, they will be awarded a "Secret Grade" upon ending the game. Much like the regular grade system of the first two games, Secret Grades go from S1 up to S9 followed by GM depending on how much of the pattern was completed, with the Secret Grade of GM awarded if the player completes the formation. In Tetris The Grand Master 3: Terrror-Instinct, if the player manages to do this in Shirase mode (a mode where blocks drop instantly and have exceptionally strict timings), the S1-S9 grades will be replaced with m1-m9 grades.
• The Witness is built around line puzzles, which mostly take a very clear form: a grid onto which the player must draw a specific line, guided by clues around the puzzle. However, there also exist "environmental puzzles" laid out into the game world itself, made up of the environment itself. Solving them involves arranging pieces of the scenery so that they create the image of a line that can then be traced. Obelisks throughout the island keep track of the ones that have been found, but their purpose is never explained. This has no effect on progressing through the main game, but it is required to find the game's hidden 'real' ending.

Racing Games

• To compete at a high level in Crash Team Racing you need to learn how to manage your boost reserves and know how to obtain and maintain various levels of turbo. The game tells you nothing about this with even the in-game hint system only vaguely alluding to the benefits of chaining turbos together and the turbo visuals not being much help beyond denoting how big the turbo you have currently is. This is softened up a bit in Crash Team Racing Nitro-Fueled by revamping the visuals of the turbo SFX to make the different reserves and strengths of turbo more readily apparent through the size and color of the flames with striking blue flames being introduced as an indicator for achieving the maximum boost, making finding the areas where you get it and knowing if you're maintaining it much less of a hassle.
• Sonic Riders has a lot of hidden stats and mechanics relating to character and gear matchups and the stats they do give you are misleadingly vague. It took nearly a decade for people to make heads and tails of these hidden statistics and them doing so led to the emergence of a new metagame and revived interest in the series.
• WipEout has a similar mechanic as Mario Kart above from Pure onwards where if you press the acceleration button right as you hear "GO!", you'll gain an instant speed boost.

Raising Sims

• The Monster Rancher games have the hidden stress gauge, which is incredibly important when raising a monster as too much stress can drastically shorten its lifespan. The only hint about its existence is the Mint Leaf item, which relieves some stress, but new players are likely to conflate being stressed with being tired (which also runs on a hidden gauge but is easier to detect) and not make the connection that it's different.
• Digimon World, in addition to evolution conditions like certain stat barriers and battle techniques learned, also has conditions for Care Mistakes and battles won, which aren't described or featured in the game at all. If a certain Digimon requires over 50 battles won it's best to keep a count yourself.
• Tamagotchi for Game Boy has two hidden stats for Stress and Selfishness that are never talked about in the game or manual, and are tied to Tamagotchi evolution and lifespan. They are possible to see in-game on the menu...but only with a cheat code, which you'd have no way of knowing through playing the game.

Real-Time Strategy Games

• In Commandos: Beyond The Call Of Duty, the developers included the documented mechanic of hiding bodies in barrels, what they did not mention is that they can explode if shot at and can be used to explode non-mission critical objectives on a map for a higher tally of mission score. It is only later in the game that this mechanic becomes critical to solving the mission, otherwise lacking the necessary explosive to destroy the mission objective.
• Dune II: In what may be an Ur-Example, at least for RTS games. These mechanics are not mentioned anywhere in the game's documentation or in-game:
  • If a harvester unit containing spice is destroyed while in the open desert, it will create a large spice field, which can then be collected by other harvesters. The total amount of spice uncovered is much more than the spice that the destroyed harvester held, which effectively allows the player to create and harvest as much spice as they need.
  • The harvester itself is usually destroyed by a hidden worm, mostly visible as a shimmer in the sand — it can be deterred from attacking the harvester by long-range units, it can also be coerced/harassed into going into the enemy's territory.
• Warcraft III: Units with the Hover movement type (such as Sorceresses and Banshees) will not trigger land mines when walking over them. This is never explained anywhere, but then again it's a highly specific situation (it never comes up in a campaign, and destroying mines from outside the blast radius is a much better option than going over them with a Squishy Wizard who can't detect them) and the Hover movement is in all other aspects identical to land-restricted movement.
  • This is largely a holdover from Blizzard's last RTS title, Starcraft, where Hover units, such as the Archon, Vulture, and all worker units, also don't trigger Spider Mines. It's slightly more relevant than in Warcraft, as the mines are more easily accessible, but once again, basically a legacy feature from earlier development models where hovering units could move off of land.

Role Playing Games

• Dark Souls:
  • You can prevent Mimic Chests from attacking you when you try to open them if you throw a Lloyd's Talisman at them. There is literally no indication that this is possible in the game.
  • While some basic enemies use parrying and riposting mechanics against the player, the game never indicates to you that these are not Secret A.I. Moves, nor tells you how to use them yourself. You have to equip a shield (or a parrying dagger) in the off-hand, then press the R2/RT button just as an enemy is about to hit you in melee to parry it, with different shields and weapons having different timing windows — all of which had to be figured out by the player community through extensive trial and error without any guidance from the game itself.
• Deltarune: There was a Good Bad Bug found in the Superboss fight that allowed the player to fire multiple bullets at once without charging their blaster. In a later patch, this was not removed, but instead added as a new mechanic, at the expense of the fight becoming much harder if you ever use it.
• Fallout 4:
  • There are enemies that hide behind cover but do not appear to have cover usable by the player. However, if you stand just behind the corner of a wall and aim down sights, your character will lean out of cover, staying mostly protected while being able to shoot back.
  • The Settlement Building system is a massive addition to the series but only comes with a very basic, barebones tutorial about a few of the essential features (food, water, beds, defense) and even then doesn't go into full detail about each of those. There are far more options in the settlement menu that aren't touched upon anywhere in the game including how to set up electrical systems for power, how "Scrapping Stations" work, how to unlock "level four" shops, and many more. It has taken serious investigation by the community to uncover the details of many of these features and some are still only partially figured out years after the game's release.
• Fate/Grand Order has a lot of hidden mechanics that are never properly explained in the game — if at all.
  • Other than the Class-based Tactical Rock–Paper–Scissors, there's a secondary one based on attributes. Man has advantage over Sky, Sky has advantage over Earth, Earth has Advantage over Man, and Beast with Star are mutually dealing and taking extra damage from each other. Attributes are never shown in a Servant's profile and the entire topic is rarely discussed, even though there are fights in which the mere existence of attributes has a vital role, like the Tiamat fight (she debuffs depending on the attributes of your party).
  • Star weight, a.k.a. what percentage of critical stars each servant gathers in their face cards, which in turn determines how likely it is to deal critical hits. While there are plenty of Craft Essences and Skills that go along the lines of "increase/decrease C. Star Gather rate", nothing in the game explains that servants already have a modifier based on their class. The ones at the top of the list are Riders and Archers, while at the very bottom are Berserkers and even below them Avengers (pretty ironic for a Critical Hit Class). If you want Star weight not to be a factor, you must either gather too few, or as many as possible (you need fifty C. Stars to ensure that each attack is a critical hit).
  • Each servant has different NP gauge and C. Star generation rates. Nothing in the game ever explains this, so depending on the servant the "Arts/Quick/Buster" combo cannot generate as much gauge as the "Buster/Quick/Arts" combo that worked so well for another servant.
  • The game NEVER gives the exact numbers of how much everything is. For example, it won't tell you that this attack buff has a value of 30%, or how much NP gauge this random Servant's Rapid Casting will fill. Craft Essences are better in this regard, telling you stuff like "Quick Card effectiveness increased by 20%", but you still don't know the base values.
  • Nothing ever talks about damage modifiers on Noble Phantasms. The difference between single target and multi-target, card type, NP levels and how they affect the damage, and each servant separately.
  • There's also a damage mechanic regarding the types of fields — forest field, sunlight field, etc. While some skills do tell you that they give additional effects in said fields (Gawain being an (in)famous example), the game never mentions that the fields themselves affect damage modifiers. Literally nothing will tell you that Heaven attribute servants take extra damage on a burning field.
  • How aggro mechanics work. Basically, servants have traits (keep in mind traits are ALSO not shown in a Servant's profile) and alignments that make certain enemies particularly focus on them with varying degrees of priority. So if you're wondering why literally everything in the game tries to murder Merlin, now you know.
  • The relation of class with NP generation rate. In particular, attacking or taking attacks generates NP gauge, but the game never tells you that this percentage is affected by the enemy's class. This is one of the main issues with the farming Metagame because Arts and Quick-type three-turn-farming is heavily dependent on what we call "NP refund", aka how much gauge you can recharge from an NP attack. For example, attacking Casters gives the highest refund, while attacking Berserkers gives the lowest. As a result, many character tier lists for farming-oriented servants use "what classes they can farm" as criteria, and the ones that can farm Berserkers are considered top tier.
• Final Fantasy:
  • In Final Fantasy VII and Final Fantasy X, there are hidden "relationship values" that affect the protagonist's relationship with party members that increase and decrease based on your dialogue choices. In VII, the person that you have the best "relationship" with will go on a carnival date with you, and in X, they will interact with you in certain cutscenes.
  • Final Fantasy IX: Characters have fixed stat growths, but the game isn't clear on the fact that equipment that give stat bonuses also provide permanent stat gains when a character levels ups while wearing them. If Zidane equips a Bone Wrist (+1 Strength) and levels up with it equipped from Level 1 to 99, he'll end up with about 3 more Strength than if he had leveled up without Bone Wrist equipped. In turn, this can encourage a different type of play where players keep their characters as low as level as possible to hold out for better late-game equipment that can be used to min-max character stats.
  • Final Fantasy XII: The game's treasure-spawning mechanics are never explained to the player. It's up to chance whether a given chest spawns in the first place and further luck-based mechanics govern whether it will contain gil or one of up to two different items. The Diamond Armlet changes the items available to a completely different set and contrary to the armlet's description, these new items aren't always better than the normal ones. The original version of the game also has four "forbidden" chests hidden in the game world that prevent the Zodiac Spear from spawning if opened.
  • Final Fantasy XIV:
    • The "Misery" debuff caused by Gremlins in certain dungeons can be dispelled via a close range emote on the affected player. Using /soothe, /comfort or /rally will remove this status effect, yet the game never tells you that.
    • Right-clicking on any positive status effect will instantly remove it from you. There's a small handful of situations where getting the wrong buff may actually cause you some trouble, but the game never explains that you can do this because it comes up so rarely that you're likely never going to need it.
    • Using the "Mammeteer" title you get from collecting thirty different "follow-type" minions makes your minions behave differently, as well as making you able to do different things with them like pretending to feed them something from your hand. The idea is that, as the Mammeteer, you're puppeteering these things to do them like a puppet on a string. The game never tells you this about the title in question, though.
• Flawed Crystals: Whenever the player healing sequence for each of the Crystal Gems, there is a secret corruption point system in play. The player automatically gets 100 corruption points whenever they start a sequence, and more are gained if you make bad decisions. If you mess up by getting every bad option in a healing sequence, you end up fighting the Final Boss early and get a bad ending.
• Harvest Moon: A significant part of your final score is determined by the level of happiness you achieve, which comes from many different sources, such as seeing wildlife on the mountain, giving your children cakes on their birthdays, talking to the villagers on New Year's Eve, and a host of other occasions (along with various things that give happiness penalties, like killing livestock). However, nothing in the game tells you about this, until the final total appears in the ending sequence. Even then, there is no visible indication of losing or gaining happiness, so you have no guidance on how to gain more happiness next time.
• The Mega Man Battle Network series:
  • Has the Program Advance, in which three specific Battle Chips are selected from the chip menu. This results in all three combining into a super attack. The tutorial never brings it up, but you can find a list of Program Advances in the chip menu available from the pause screen that lists all the Program Advances you've discovered.
  • Some program advances are hinted at by characters who luck onto them, but they're optional conversations.
• Pokémon:
  • The games have never even alluded to the existence of the effort values (EV) mechanic by which stat gains on level-up are determined throughout the series.
  • Starting from Gold and Silver up to Scarlet and Violet, there is a extremely rare chance for a Pokémon to contract Pokérus, a viral infection that is very unhelpfully described and is only stated to make your Pokémon grow faster. What this actually means is that your Pokémon infected with Pokérus will gain double the effort values earned from battle, making it much easier to max them out. It is also possible to spread Pokérus, which is also not described and can be extremely beneficial when trying to retain Pokérus or raise multiple Pokémon at once.
  • So, so much with Pokémon breeding. The franchise never tells you anything about how it works beyond "put two Pokémon in the Day Care and you might get an Egg". To name some of these internal mechanics:
    • Pokémon can only breed with each other if they share the same Egg Group, which is basically a separate classification system that sorts who can breed with who. Furthermore, two given Pokémon can have differing compatability rates depending on if the Original Trainer of the two Pokémon are the same or different, which influences the chances to obtain a Pokémon Egg every 256 steps. The only indication that either of these two mechanics exist is by talking to the NPC standing outside the Day Care (in pre-Generation IX games), and it is very unclear that the NPC's lines are any indication of these factors.
    • Ditto can breed with any Pokémon that can produce an Egg. This makes sense in hindsight from a logical standpoint but is not stated in-game.
    • In games before Generation IX, Pokémon that retroactively received a Baby stage must hold a specific type of Incense to produce an Egg of that Baby Pokémon. Nowhere is this stated in any game.
    • Differing Pokémon have different hatch speeds, which are called Egg Cycles. 1 Egg Cycle is equivalent to 256 steps, and once a Pokémon Egg reaches the requisite number of Egg Cycles, it will hatch. The game also fails to explain that some Abilities can halve the number of required Egg Cycles if a Pokémon with that Ability is in your party, including Flame Body, Magma Armor, and Steam Engine.
    • While most Pokémon simply get their base moveset plus possible level up moves upon hatching, there is a possibility for them to learn an Egg Move, which is a move known by one of the parent Pokémon that can't otherwise be learned by that species' evolutionary line. Which Pokémon get Egg Moves, and which Egg Moves are possible for each Pokémon that can have them are not explained and will likely require a guide. Furthermore, the Pikachu line can only learn its Signature Move Volt Tackle through breeding, and only if one of the parents holds the Light Ball item. To make this even more confusing, in Sword and Shield this mechanic was tweaked such that a Pokémon that knows an Egg Move can teach that move to any Pokémon of the same species with an empty move slot if they are in the Nursery together (regardless of gender), and in Scarlet and Violet a Pokémon with an empty move slot holding the Mirror Herb item can learn an Egg Move from any other Pokémon in the same party during a Picnic if another Pokémon in the party knows a move that the target Pokémon can inherit as an Egg Move.
    • Breeding allows you to produce a Pokémon with individual values and Natures inherited from their parents. By default, a hatched Pokémon will inherit 3 random IVs but can be manipulated by giving the parents certain held items, like the Power items and/or the Destiny Knot. Natures are normally random, but giving one of the parents an Everstone will allow you to pass down that parent's Nature to the hatched Pokémon (although specifics vary by game).
    • Starting from Generation IV, there is a special mechanic unofficially dubbed the "Masuda method", named after Junichi Masuda, who claimed that the mechanic was added to encourage players to perform online trades. Essentially, if two Pokémon of different original languages breed, the chances that the hatched Pokémon will be a Shiny Pokémon is rerolled additional times, effectively making several times more likely to get a Shiny Pokémon. This mechanic was completely unmentioned in the series until Pokémon Scarlet and Violet, where Jacq mentions it in one of his Biology classes.
  • Pokémon Gold and Silver: Shiny Pokémon first appear in this generation, but their introduction with the Red Gyarados comes basically from nowhere and no NPC player explains the mechanics behind their encounter rate. This led many young players to assume that Gyarados alone was one of a kind and that any other Shiny Pokémon encounter was a glitch of the game.
  • Pokémon Ruby and Sapphire introduced the concept of Pokemon having a "nature", i.e. personality. That this affects their stats is not explained until HeartGold and SoulSilver.
  • In Pokémon Yellow there's a minigame that will only activate if you have a Pikachu that knows Surf. The only way to teach Surf to a Pikachu is by beating a particular tournament in Pokemon Stadium using a Pikachu transferred from Pokemon Yellow. And the minigame isn't even obvious, a random NPC will only say something different if you have a Pikachu that knows Surf with you.
  • Pokémon Sword and Shield: In a first for the series, the game has a pseudo-open world area called the Wild Area where you can roam about and encounter Pokémon in the overworld, including Pokémon that are much higher level than you. To balance this and prevent players from potentially ending up with a Pokémon that is much more powerful than their current progress in the game, the developers made a very insidious tweak to the internal catch formula such that attempting to catch a Pokémon that is a higher level than the highest level member of your party inflicts a massive catch rate penalty to the point where the odds of catching it are close to zero. Even more tricky is that the game does not tell you that this mechanic goes away once you clear the main campaign, and also does not apply to Max Raids or Dynamax Adventures (in The Crown Tundra).
• Recettear: An Item Shop's Tale:
  • Getting bonus XP for just right prices is never explained, with the tutorial instead focusing on how to gain the most money in each transaction. This combined with the also unexplained need to level up customers so that they can afford more expensive items tends to lead to first-time players getting an early game over.
  • Customers each have an affinity type that can be raised up by satisfying their demands either by buying or selling a price that they feel comfortable with. This makes it easier to get bonuses and more money from them in future sales. The game acknowledges this mechanic and shows a heart next to the customer when the affinity goes up, but does not keep track of the affinity values of each customer. It's up to the player to figure out where they stand, or even if they've maxed out the affinity.
• The Super Mario Bros. RPG games:
  • Mario & Luigi: Bowser's Inside Story: Whenever Bowser inhales an enemy, steals helpful items in battle, bring in certain enemies for the Mario Bros to fight, or uses it to find hidden Blittes, you can press X and Y repeatedly to greatly increase the strength of Bowser's vacuum.
  • Paper Mario: Sticker Star:
    • Mario can find certain sticker "upgrade spots" around the world — putting a sticker in one will turn it into an equivalent or better one. They're usually distinguished by different types of flowers in a hexagon shape. Exactly what these spots are, how they work, and how they upgrade your stickers is never explained in-game.
    • Things and Thing Stickers are not fully explained by the game; they have action commands, the majority of which are just "Mash the A Button". There are a few exceptions, such as the cake, which requires you to use the 3DS's microphone to blow out candles.
• Tales Series
  • Tales of Symphonia has Relationship Values for different characters, and how they feel about main protagonist Lloyd Irving. Whichever character is designated as Lloyd's soulmate will get extra scenes with him, along with potentially changing party composition late-game by making the fake Face–Heel Turn of Zelos into a real one, which replaced Zelos with Kratos. However, the game doesn't tell you about the existence of these values and also doesn't inform you how they can be increased.
  • Tales of the Abyss has the ability to power up Mystic Artes, depending on where you are in the story or if you've fulfilled certain conditions. For instance, if Fon Master Ion is traveling with the party, you can hold down a button during Luke's Mystic Arte to have Ion deliver a second no-cost follow-up Mystic Arte. The only way to know about these Mystic Arte boosts is through looking up how to use them online, because the game never tells you that you can do it, let alone how you can do it.
  • Tales of Berseria
    • The game allows you to chain Mystic Artes together should you use one, as long as each character has enough in their Blast Gauge to use one. Also, the Mystic Artes progressively increase in level down the chain, and this can last until you either choose to stop, or run out of BG. You can even keep going after your target has run out of HP (indicated by a "Crush!" graphic), just in case you feel like going ham on your enemy. However, the game doesn't even hint that chaining Mystic Artes together is possible.
    • Healing spells are affected by SG quantity and other effects, which are neither intuitive nor explained. Under the wrong circumstances, it's totally possible for even the strongest spells to heal pitiful amounts. In higher difficulties, they're basically only good for removing status effects, making it better to restore health with Break Souls and items.
• Undertale never quite explains how its Mercy Invincibility mechanic works. The player can tell that it happens, but what the game won't tell you is that the more damage you take in one hit the longer it lasts. It also doesn't tell you that taking only one point of damage doesn't trigger it. Which you find out the hard way in the Route Boss fight with Sans, who uses Death of a Thousand Cuts (one point of damage per frame, aka 30 per second) to take you down, as it never triggers Mercy Invincibility and you always take the full brunt of it.
• Xenoblade Chronicles 2: There are several mechanics that aren't properly explained, or are explained very poorly and don't cover the topic well enough. Blade Combos, for example, are not properly explained. You are told how to do them but are not told what type combo leads to what. For the Merc group, a blade's gender is important for some missions. While male and female blades are easy enough to tell, one particular story blade has their listed gender as "4", meaning they are genderless.

Shoot'em Up Games

• Battle Garegga has hidden Option formations that can be activated by missing a particular item type a set number of times then picking up the next Option item. This went unexplained in-game until the Battle Garegga Rev.2016 Updated Re-release, which features a gadget that shows the number of each type of item you've missed in a row for the purpose of these hidden formations. These special formations are not required to complete the game.
• Touhou Kouryuudou ~ Unconnected Marketeers: The in-game manual doesn't mention that certain enemies drop more money if they are killed quickly after spawning.

Survival Horror

• Resident Evil games starting with Resident Evil 4 feature a hidden Dynamic Difficulty that increases the challenge when you do well, and decreases it when you do badly. For example, the Water Room has an onslaught of enemies on your first entry. After dying and continuing, there are fewer enemies than last time, and the number of enemies which use shields has also decreased. Meanwhile, if you enter the Water Room doing particularly well, the number of enemies and enemies with shields will also be higher than normal. The only exception is Professional Mode, which locks the difficulty at its highest setting and doesn't lower it no matter what. This dynamic difficulty is never explained in any of the games that use it, but it's made so that the game always feels just hard enough to be a challenge but just easy enough to not be frustrating.

Tabletop Games

• Dungeons & Dragons, Advanced Dungeons & Dragons 1st Edition Dungeon Master's Guide.
  • If a player has their Player Character perform actions contrary to their Character Alignment, their alignment can change appropriately. If this happens, the Player Character will lose a Character Level of experience as punishment. Dungeon Masters are instructed to not inform the players about the penalty for changing alignment. This is so the player will be punished if they have their character change alignment for their own convenience.
  • Player Character magic-users can perform research to develop new spells. Dungeon Masters are told not to let the player or their Player Character know exactly how the process works or their chance for success. The Player Character just have to spend their time and money and hope it works.
• Mao hides the ruleset, as well as prohibiting talks about the ruleset. New players need to learn the rules by trial and error.
• Paranoia: Rulebooks use the same color designations as the setting. The Game Master's materials, including rules that are not directly relevant to the player, are classified as Ultraviolet, while player supplements are classified as Red. Accessing material above your clearance grade is treason.

Tower Defense

• In Plants vs. Zombies and its sequel, waves are triggered after the zombies in the previous wave take enough damage, or, failing that, when enough time passes, meaning that "stalling out" the first few zombies in a level will give you more time to collect sun and plant sunflowers, but you wouldn't ever figure this out without experimentation. Expect any Game Mod that actually mentions this mechanic to drastically reduce how much damage is necessary to do so.

Turn-Based Strategy

• Advance Wars has some hidden diminishing returns mechanics that they never tell you about:
  • Luck and terrain stars scale with health, meaning a unit with only 5 HP can only get half as lucky and only gets half the defense it normally gets — this is a driving reason why Lash is seen as such a noob trap, as her strengths quickly melt away and her units, like Grimm's, quickly lose all their steam as they suffer damage while her CO Powers only power up units on good terrain and with full health.
  • Each time you use a CO Power, it becomes more expensive and charges up more slowly. There is a limit to this penalty, but you're not likely to see it in a match unless you're deliberately trying to see it. The game also penalizes you by taking 20% off of your remaining charge if you use a regular CO Power and have charge left over — this is to stop characters like Andy, who has a 3 star / 6 star meter, from using two regular CO Powers in a row in lieu of one Super CO Power.
  • While the game tells you your CO Power's meter charges up during combat, it neglects to tell you the meter charges up faster when you are losing units — shooting down an enemy unit will only charge up your meter at 25% the rate of losing that same unit. Also, as the charge is tied directly to the financial value of units, Kanbei units charge the meter up faster, while Colin and Hachi charge the meter up more slowly.
• Fire Emblem:
  • For a series-wide one: child units and their stats/growths. In games where the children of your units are usable (Fire Emblem: Genealogy of the Holy War, Fire Emblem: Awakening, and Fire Emblem Fates), there is a hidden calculation done to determine the unit's stats and growths. Typically this is by having the child unit's own stats and growths be shaped by the stats and growths of whoever their list of potential parents are (since they always have one consistent parent). For example: Lucina by default has a semi-Fragile Speedster growth and stat spread, but her potential mothers will cause those stats and growths to vary, such as being a Lightning Bruiser with Sully as a mother versus a semi-Master of All with the Avatar as her mother. None of this is outright stated, so you would have to look outside the game to notice how the calculations work.
  • Growth rates are a set of values that determine how often the unit increases a stat upon leveling up. These values are never shown to the player, so players that do not have the information in mind have to infer their growth rates through observation and their class, but even that's not perfect. In addition, starting with Fire Emblem: Shadow Dragon, growth rates are also affected by the class the unit belongs to.
  • Support is a mechanic where paired units fight better by being in proximity of each other. It is first introduced in Fire Emblem: Mystery of the Emblem, but the game doesn't directly tell you of its effects or the recipients.
  • Part of what makes Fire Emblem: Thracia 776 so difficult is that many of its mechanics that could help give the player an edge are never explained. For example, every unit has a factor called "Follow-up Critical Multiplier," which multiples the unit's critical hit rate upon dealing a follow-up attack (a second attack if the unit is faster than the enemy).
  • Fire Emblem: Radiant Dawn:
    • There's a bonus EXP system that can help level up weaker units, but will only raise three of their 8 possible stats. This can be circumvented by only using Bonus EXP to raise a unit to 99/100 exp so they'll level up the first time they do anything in the next battle, but can also be exploited to raise the weaker stats of a character that has already capped their main stats, as if leveling up the main stats is no longer possible, the BEXP system will instead give those 3 points to skills with lower growth rates that might normally be very unlikely to ever go up.
    • There are hidden treasures on nearly every map, which can be picked up by moving a unit onto specific tiles. Most characters have a random chance of finding the item (raised or lowered depending on Biorhythm, which the game also doesn't explain), but it's guaranteed for Thief classes. Other games featured this mechanic, but only in desert chapters, and it was always hinted at in dialogue. Making this even more confusing, some treasures were removed or changed in the English localization.
    • The "pacifism" system causes certain characters to not attack certain others. This usually applies to family members, like Brom and Meg, or closely-connected allies like Zihark and Lethe. If one of these characters is an enemy, they will never attack the other. Under player control, the Attack option won't appear in the menu if you attempt to have these characters fight.
  • Fire Emblem: Awakening: The game has a hidden mechanic with Supports where each character gains different amounts of Support Points in battle with other characters, making some easier or harder to obtain the next Support Rank and conversation. For example: Lissa gets more Support Points with Vaike compared to her brother Chrom, who in turn takes more Support Points to progress with Vaike compared to Lissa. It isn't enough of a hidden mechanic to make getting Supports hard, but it isn't explained at all, so players may wonder why certain characters seemed to have gotten Supports quicker than others.
  • Fire Emblem Engage has a rare example overlapping with Suspicious Videogame Generosity. During Chapter 11, all enemies besides the bosses have an invisible skill preventing them from triggering Critical Hits when initiating combat.
• Heroes of Might and Magic III:
  • Visiting a Stables on the Adventure map with Cavaliers in your army will upgrade them into Champions for free. This was most likely added as a way to not make external Stables useless for Castle since they can build Stables in their towns, but isn't referenced anywhere in the game.
  • Cavaliers and Champions have the Jousting ability, which causes them to deal bonus damage based on the distance they traveled before attacking. Although it isn't listed anywhere, Pikemen and Halberdiers are immune to this bonus.
  • Libraries of Enlightenment normally require a level 10 hero to enter. If your hero has Diplomacy, a skill that normally reduces the cost of surrendering and makes neutral creatures more likely to join you, this requirement is lowered by 2 per rank in Diplomacy, down to level 4 at Expert. This is massive overkill since it's very unlikely that a level 4 hero would even have Expert Diplomacy.

Wide-Open Sandbox

• Endless Sky: The player has a reputation with every faction in space, but this figure is hidden and can only be seen by reading save files with a text editor. The fact that attacking ships from a particular government will make them hostile is pretty intuitive, but the fact that you can gain reputation points by repairing their damaged ships, or in some but not all cases by killing their enemies, is less so, and isn't in any tutorial. Certain missions can also dramatically alter your reputation, and you often don't get any indication of it until a faction starts or stops shooting at you.
• The Lord Of The Rings Return To Moria: Has Treasure Piles throughout from which the player can extract 3 slots of items, with the most common — gold pieces, being useless, however, they can be placed back into the pile for a chance to pull out more useful items like gems.

Other

• The Trope Codifier comes from early race-car races, where engineers would improve on engines and aerodynamic profiles but keeping them hidden from their competitors — multiple cylinder engines, pressurized fuel injectors, turbochargers, differential steering, assisted breaking and even levitation^note as in flying aircraft come from these early efforts. So when it comes to games and their engines, Developer's Foresight usually strives to include some hidden gimmick to reward their pilots... um, players.
• Some ancient coins only had an impression on them on one side — because of center of mass displacement, this caused the coin to end up with the heads side up most of the time, or at least a fair distance away from the 50-50 probability we count on today's coins. Anthropologists and historians have noted that there are such coins that have been manufactured to subvert this mechanic entirely (either by intent or mistake) — and might have been used in gambling and games of chance for their hidden properties.
• The Discord mobile app secretly allows users to toggle between the current build and the next experimental build by tapping a ✨ emoji anywhere in the app to bring up the emoji pop-up, then pressing and holding the ✨ emoji in said pop-up for three seconds.

---

If you are here looking for an automobile engineer under a vehicle...

* gets into character *

Well, there's your problem! This here trope is not that!