Good Bad Bugs / Turn-Based Strategy

• Worms: With quick fingers it is possible to switch to the rocket launcher and the mini gun at the same time, causing the minigun firing code to fire rockets. There is usually a significant chunk of the level missing afterwards.
• Colonization has a bug on the trading screen which lets you sell resources that have been forbidden through a Customs House. Naturally, most players don't bother installing the patch to fix this bug, as it makes the game a good deal easier towards the end.
  • In fact, the open-source clone FreeCol reproduced this as an optional rule.
• The original Civilization had the Settlers bug: if you ordered a Settler unit to perform some multi-turn task (like irrigating or mining a square), it'd usually stay inactive until the task is completed, which e.g. in case of mining a mountain would take up to 9 turns. However, if you canceled its current action and then ordered it to do it again, the engine would interpret it as if the Settler already spent a turn doing it and continue from where it "stopped". This trick could be repeated until the task was complete. Sure, it's a lot of manual clicking but it allowed you to fully irrigate/mine the area around AND build roads your city in a few turns, which is crucial at early stages when every Settler counts.
  • You could also put this same Settler on a transport and use this bug to build a road and then a railroad in the middle of the ocean. A ship could carry cargo halfway across the map if you have an ocean railroad in place for it. You'd have to end a unit's turn when it's loaded into the ship, but other than that you can go VERY far.
  • In addition, save games did not keep track of which units had already used their turns, so long as you still had at least one unit who had a move left. You could play through an entire turn, save the game, load the save file, and play another turn without letting any other nation get to play.
  • In Civilization II: Test of Time, there were game modes with multiple "worlds", which mapped to each other 1-to-1. Normally, only certain units could move between certain worlds in certain circumstances, which was enforced by unselecting the active unit when the player manually flipped between maps. However, if the player controlled a city on the map a unit was on and another on the map they wanted the unit to get to, then they could select the unit they wanted to move, enter the city screen of any city they controlled on the starting map, use the buttons in the city screen to cycle over to a city on the target map, then exit the city screen. The unit would still be selected and could thus be given movement orders, so as long as the square they would be moving onto on the target map was passable to them (all worlds used land/sea designations in some way), they would glitch onto the new map mid-step.
  • In Civilization IV, getting a Great Person would allow you to expend that unit and put research towards a new technology, initiate a Golden Age, build a unique building, boost your culture, etc. Also added in this game was the ability to give multiple orders at once to a unit, by holding shift while clicking their abilities. It was soon discovered that holding shift and clicking on the abilities of the Great Person did not cause them to be deleted. One game advanced from the Ancient World to the modern Industrial Era through the continual brilliance of Moses. Sadly, this bug was fixed with the expansion packs.
  • In Civ 5, on the higher difficulties, you can leech the gold boost that computer players get by exploiting them with a good army; take over one or two cities, then offer one city back and peace for a whole lot of gold. Go to war 10 turns later, repeat. Usually, conquering a civ only gives you a small fraction of their gold and the rest is lost (for game balance and other reasons), but this way, it can be extracted from weaker civs. This one isn't entirely a Game-Breaker since it requires some work and might even make a little sense, besides the computer being far too slow to learn what you're doing (if it ever does). Before the 2011 patches, there were a lot of other ways for players to mess around with numbers in unintended ways.
    • There is also another glitch/exploit that utilizes trade system. Basically, starting a war cancels all agreements you've made with someone You could - however - trade long term investment (strategic resources) for one-time payment. And if you start a war very next turn, the game automatically broke the deal and give you all your resources back - which means that in the end you get both the money and your goods. Oh, and for added irony you could use that money to fund an army that beat said player.
    • There's a similar (and more convoluted)exploit found here that combines the ability to trade per-turn resources for one-time payments and cancelling the trade the next turn without getting involved in a war at all. In short, the trick combines being able to trade one-time payments for per-turn obligations, the rule that says that if any part of the per-turn trade is unable to be completed the whole deal is off, the fact that forts can be used to replace improvements like plantations and mines and the first turn of building the fort removes the existing building, and a few more. Essentially, you offer a luxury resource of which you have only one source to a computer opponent in return for receiving gold, and then break the deal the next turn by losing access to that luxury when you start building the fort, which means you get their money and can then cancel the fort and rebuild the mine/plantation to do it again. What happens if they don't have a substantial amount of gold to make it worthwhile? Well, you can get around this by first offering the gold to them in exchange for a certain amount of gold per turn back to you, and then immediately use the gold you just gave them to sell them the resource. Since the gold per turn they are giving you in return for the flat gold payment is not associated with the trade involving the resource, it does not cancel out when the resource loss cancels the other trade. Note that not only does this trick give YOU a lot of gold, it obliges the computer to keep giving you money to their financial ruin, AND if the trade offers were generous enough to the computer, makes them love you all the more while they are driven into bankruptcy.
    • Native villages/ancient ruins in Civ IV and V could also bring...interesting results. In IV, there was no upper cap on what tech you could get from them - so it's entirely possible to find perfectly working modern technology (up to freakin nuclear fission) in some tribal village on the remote corner of the map. In V, they fixed that mistake by limiting possible techs to the classical era... but, at the same time, give you a chance to upgrade your units. Again, there is no limit on how high this could get - so, if you are lucky, your cities could be guarded by machineguns and riflemen. In 1000 BC. In VI, they can in fact have technologies and civic boosts of all ages, but it will always be one you would have researched soon anyway. This leads to the puzzling sight of a remote tribal village knowing about nuclear fission, or, alarmingly, fascism.
    • When founding a Pantheon, you receive a small bonus to go with it. However, if you press Escape at the same time as clicking 'Found Pantheon', you get the founding bonus but can choose another one. Or the same one. Repeat this as many times as you like for as big an early-game steroid as you like, such as having fifty Settlers in the Ancient Age.
• X-COM: UFO Defense allowed your soldiers to throw grenades through the ceiling. This was incredibly helpful when there was a Muton on a roof.
  • Ammunition for tier one (ballistic) weapons costs money, and you have to manufacture or capture clips for tier three (plasma) weapons, occasionally at significant costs. Unless you make sure to eject the clip before the mission ends: because the game only checks if a clip has zero, or more than zero, rounds remaining, a clip with at least 1 round remaining counts as a full clip. Free ammo!
  • X-COM had another gem of a bug: Whatever you set the difficulty to, the game played on the 'Beginner' difficulty. This bug went unknown for years, because the game was THAT damned hard. And it gets better: when MicroProse was throwing together the mission pack sequel Terror from the Deep, they solicited feedback from players. A big chunk of players who responded were hardcore strat gamers who complained that the game's higher difficulty levels weren't hard enough. MicroProse's response? Make TFTD's Beginner difficulty equivalent to what Superhuman was supposed to be in UFO Defense.
    • There's also the pathfinding bug in UFO Defense for the blaster launcher, where the majority of the time the enemy units would launch it directly above themselves, even if there was a roof above them, leading to many times in indoor maps where there would be numerous random explosions going on out of your line of sight for, from your perspective, no reason.
  • XCOM: Enemy Unknown, in its expansion Enemy Within, has the "carryover bug", where an upgrade to the MEC's weapons' damage is carried over to subsequent games, where it can be applied again to further boost the damage.
• In Heroes of Might and Magic III, there was a campaign (Rise of the Necromancer) in which you are given two very powerful artefacts; the Armour of the Damned (that makes every enemy weak, slow and useless in battle) and the Cloak of the Undead King (which turned the rather useless skeletons gained from Necromancy into the much more useful, ranged Liches). These allowed you to quickly build up an invincible army of liches that would number in the hundreds by the end of each map. You only get one of each set, but the campaign would also take copies (as well as the component pieces). If you used the Dungeon's Artifact Merchants to gather the components again, you could go through the rest of the campaign with multiple Heroes made unstoppable with these artifacts.
• The Apple II game Taipan! had the player as the captain of a trading/fighting ship in the Far East. In Hong Kong, one of the ports you could visit, was a moneylender (loanshark) with a ruinous interest rate. Unfortunately for Elder Brother Wu, he didn't understand the concept of negative numbers, so you could borrow 100 and pay him back 200, at which point he'd start paying you interest at his usurious rate.
• Galactic Civilizations: The diplomacy screen lets you trade basically anything in the game: from single ships and technologies to treaties to entire solar systems. And of course money. Different techs and buildings boost your diplomatic abilities, effectively giving you the upper hand in negotiations, thus letting you acquire more ships for money, or more tech for your money, or - that's right - more money for your money. Things don't stop there, though. You can make contracts where you and the AI pay each other a certain amount for x number of rounds. For some reason this makes both parties richer every round, effectively granting you infinite cash. Another good thing is that the AI just can't handle that much money, utilizing only a fraction of what it has available, while you crank out disgustingly strong fleets in no time at all. Too bad GalCiv doesn't have a multiplayer mode.
• Super Robot Wars:
  • Super Robot Wars Alpha 3 calculates the energy cost to move in the air or in space based on how many tiles the unit has actually moved on screen, but the amount of energy to refund from cancelling a movement based on how many total squares were ordered to be moved. Cancelling movements partway through can thus allow any unit to infinitely recover energy, albeit excruciatingly slowly.
  • The first Super Robot Wars: Original Generation game had a bug that caused all character themes to be overriden by a particular enemy unit's theme when he comes into play. The theme was so Awesome, however, that the feature, now dubbed "Trombe Override" (after the theme music, named ''Trombe!'') is a regular fixture of the series.
  • Super Robot Wars Judgment had a bug where, if you applied an item to a unit that would be lost due to game events (such as Mazinger Z or Layzner), whatever they would replace (Mazinkaiser and Super Layzner/Layzner Mk-II) would get those bonuses even though the item would be returned to you.
  • Super Robot Wars UX has perhaps the only case where a bug being a Game-Breaking Bug is what makes it a Good Bad Bug. Having Demonbane and Master Therion use their Shining Trapezohedrons against each other will crash the game on the spot; what makes this a good bug is that it perfectly recreates the source material, where if they ever did this, it would cause Azathoth to awaken and reality would instantly pop like a soap bubble.
  • Super Robot Wars Z2 had some interface tweaks between the first and second parts. One of the tweaks opened up a bug that allows you to have all of your party members take a turn at using the Sub Orders system, instead of the normal limit of twenty. While this can be used to gather enormous amounts of money very quickly, a less game-breaking application is to gather kills and PP on the units that you don't normally deploy on a given run. Another bug allows you to select and then deselect the carryover option when starting a new game to stack the carryover bonus money, allowing you to gain enough money to max out all of your units before the game even begins.
  • Super Robot Wars Z Tengoku-hen has a glitch where if either Hibiki Kamishiro or Nono use items in their inventory and then transform into their super modes, they can reuse the items that they already have used again. By the end of the game, both of them each get an even more super mode which also has the glitch, letting them use their items a third time.
  • Super Robot Wars 30 has Suzaku and the Lancelot siN, due to an error in placement for skillsets, cause Potential L9 to stack twice whenever Suzaku's "Curse of Geass" ability (which adds Potential L9 as one of its abilities). In practice, this makes him a powerhouse at critical HP levels as his hitrate and evasion skills are raised to a base 90% regardless of other factors and damage reduction boosted to at least 99%'. Combined with siN's "Blaze Luminous" ability, which reduces 1000 damage from all sources for 5 EN and his crit chances skyrocketing to over 100%, meaning that not only is Suzaku a Stone Wall, he's also a killing machine.
• One of the patches for Master of Orion 2 introduced a very odd AI quirk. Every so often an AI controlled race might notice that your science and military make you significantly stronger than they are. So it would decide you are a threat and declare war on you. A few turns later the AI will take a look at you again and realise they can't possibly win a war against you, so they will ask for peace - often throwing in one of their planets as an incentive. This can happen repeatedly - so the enemy literally hands over their empire to you one planet at a time.
  • Masters of Orion 2 also features a bug that lets your ships become invincible. The best stealth field module makes your ships untargetable and immune to damage if you don't attack that turn. There's also another module that lets your ships act twice during a single turn. Combine the two and you can use your first action to attack, then do nothing on the second one (which the game treats as you not attacking that turn) to become untargetable to the enemy.
  • In the first Master of Orion the AI cannot manage more than one or two attacks at a time. This allows the player to win simply by hitting his enemy at a faster rate.
    • It also won't attack planets it lacks the technology to land on, even if it could bomb them from orbit.
  • Among the many bugs present in Master Of Orion 3, one was that the AI would always bombard planets from orbit before dropping troops to invade. Once technology had advanced far enough for planet-destroying weapons to be developed, this made the AI incapable of ever invading planet at all, since they would always destroy them first. While this did mean losing planets, it also meant that past a certain point in the game the AI could never expand their empires and become more powerful, while the player could still expand by conquering planets or rebuilding the remnant asteroid belts back into planets (which the AI would never do). In extreme cases, AI empires could cripple each other by destroying all their planets, while the player just stayed out of it all and eventually won by default.
• Endless Space used to have the exact same AI bug as Master of Orion 2 above, where the AI would sometimes repeatedly declare war on you, only to immediately ask for peace. Fitting as the game is pretty much a Spiritual Successor to Master of Orion 2. While the bug was fixed by improving the AI and adding a minimum time you have to wait before you can declare a war again after agreeing to a ceasefire, another very similar AI quirk was still possible the last time I checked. If you have a large amount of extra minerals or trade goods, and one of the AI factions really dislikes you, you can use them to get free stuff. When they declare war on you, offer a ceasefire and hand them enough goods in return that they will not only agree, but also throw in a planet or some technology. When the ceasefire ends the AI, who still hates you, will declare war again, cancelling all trade routes you had with them and returning any minerals/trade goods you agreed to trade to them back to you. Repeat the process for as long as necessary for free stuff, then crush them with the armada they've helped to finance.
  • There was also a bug in the early version of the game that allowed you to eliminate another faction by literally buying their empire from under them. In practice if you could do this you either had enough money to win by economic victory anyway, or the faction had so few planets they were insignificant, but it was still pretty funny. Later patches made it so that the AI will never sell you all of their planets.
• Fire Emblem
  • In Fire Emblem Gaiden the player is normally expected to have The Hero use the Sword of Plot Advancement in order to damage the Final Boss after a certain point because said sword is a Villain-Beating Artifact. However, the game code that normally forces attacks to miss (as to force the player into beating the final boss in the intended way) fails to work on the fixed-accuracy Nosferatu spell due to a programming error. As a result, it became possible to kill Duma with Nosferatu, which was eventually added to the remake as an Easter Egg.
  • There's a glitch in the seventh Fire Emblem game that lets you control your enemies. By placing a mine on the ground, waiting for an enemy to step on it, and resetting the game while the HP bar decreases, you are able to move your enemies just like you would your own units. It's only for one turn, but that's enough for you to make everyone drop their weapons (or hand them to you) if you wish. This trick also works with squares where a Torch staff is used and lava tiles.
  • The "Uberspear" that gives major boosts to Vaida's stats when she appears as a boss is not a bug. Being able to steal it off of her and enjoy the stat boosts yourself is.
  • In the preceding game, you had Fae, who had a Dragonstone that let her hit hard, but wore out after only thirty uses and couldn't be repaired or replaced. This made her very much Too Awesome to Use. Enemy Manaketes also have Dragonstones, and theirs don't wear out, but they don't drop and can't be stolen by your Thieves. However, for some reason, enemy Thieves can steal them. If you can get one of these Thieves to steal from a Manakete (like through a Berserk staff), you can then steal it from the Thief and give it to Fae, allowing her to attack without fear.
    • Due to the application of enemy stat boosts on Hard Mode, certain recruitable characters ended up with massive bonuses, as long as they appeared on the map after the first turn. Later games would turn these Hard Mode Perks into more of a standard feature.
  • In Fire Emblem: The Sacred Stones, that enemy control glitch (which can now be activated by normal combat damage as long as it's the enemy's turn) still lets you make all the enemies hand their weapons and equipment to your team. Including, say, claws, teeth, and eyes, which the game treats as weapons. And if you then equip eyes, you can train any character, no matter their class, in dark magic. You can also give rare items to a gorgon egg, which will mark its whole inventory except the first item as "items which will be dropped when I die", wait for it to hatch, and kill it, and when you do all the items will be fully recharged, even the unique items which were specifically designed to be unrechargable.
  • As well, you can recharge elixirs by letting an enemy thief steal one and then kill him. Same thief trick also serves to recharge Myrrh's Dragonstone.
  • In Fire Emblem: Genealogy of the Holy War, there's a bug that lets you put one of the Game-Breaker Legendary Weapons into a shop, allowing a better statted character to buy it, and assumedly use it.
    • And while their status as "Glitches" or "Bugs" is highly debatable (As both are results of correctly working systems in the game), there's at least 2 tricks that allow your to pair The Hero Seliph with his half-sister, and resident Mysterious Waif, Princess Julia. (First involves forming a particular square of units and not saving for 2 and a half chapters; the other involves having Seliph and Julia glued to each other until she's captured, then have Seliph wait next to a Brainwashed and Crazy Julia on the final chapter).
    • And finally, there's a possibility that even the plot itself can fall victim to a glitch, or exactly the unbridled WRATH of the Random Number God— it's possible for Ethlyn and Quan to kill the Thracian Knights in Chapter 5... the one where, plot-wise, they're supposed to be murdered.
  • Fire Emblem: Radiant Dawn
    • An enemy Bishop with a Rescue staff can place an enemy on top of a pitfall trap in Chapter 3-11. This allows a unit with Pass to move through the square unimpeded, as well as creating a very silly situation where a unit can engage an enemy and then fall into a pit as soon as they try to pass through the recently occupied space. More importantly, you can take advantage of this by placing your own flying units atop one of these spaces (and you recruit a LOT that chapter) and then moving your non-fliers past the pitfalls. The game will not allow two units to occupy the same space; therefore, it will not stop them as they go over the pitfalls.
    • Seemingly to avoid any issues, Staff weapons are capable of being used as melee weapons, though only as Counter Attacks. For some reason though, most Staffs have higher than average crit chance, with the Matrona staff having a guaranteed crit chance. Due to this, it is possible with some preparation to have a character crit enemies to death with what amounts of bonking them with a healing staff, despite the game obviously not intending for that to be a strategy.
    • There is a pretty famous one involving the skill Adept. Adept gives the unit a speed percent chance to make another attack, meaning it has a somewhat low but still decent chance to hit when using a unit with good speed. If using a Brave weapon though, Adept will still have a chance of activating on the extra attacks as well. Where it becomes almost certainly an unintended oversight in how the skill works is that if a character has the Resolve skill - which gives a 1.5 multiplier to speed and skill if below half HP - then the character has a huge chance of making every attack activate Adept, meaning instead of up to four attacks, the unit can make eight, which can make almost every enemy in the game crumble unless they have insanely high defense or some kind of No-Sell.
  • Fire Emblem Heroes
    • When randomly generating units for the training tower or Tempest Trials, ensures that legendary weapons or exclusive skills don't go into the unintended hands. An oversight on the weapon Alondite caused one of its wielders, Zelgius, to randomly generate with a random non-legendary sword in the training tower and completely unarmed in Tempest Trials, because Alondite was coded only for the Black Knight, who was a free unit who could not show up as a random enemy. This was eventually fixed in 2.3 as an undocumented change.
    • During one period of the game, a glitch was made where when doing maps with the retry option, if you kept redoing the fight, it would cause the amount of Skill Points (SP) to continuously double, meaning you could get up to getting nearly 800 SP for defeating a single enemy. It was fixed shortly, but the developers opted not to punish people for using it.
    • When Lucia was added as a unit, her weapon's effect had a form of No-Sell that prevented out of combat effects or skills from applying to her. A mistake with the coding though caused the effect to only half apply to her allies, meaning an ally unit with one of the Save skills meant to shield allies would protect her, but Lucia would still be able to counter the attacker and not be hurt. This briefly made her insanely broken as a result, leading to it being fixed quickly.
  • Fire Emblem: Three Houses: Linked Attacks would only trigger their bonuses when another unit is in attacking range of an enemy. Due to an oversight though, characters with spells that could hit from far across the map could essentially always give bonuses to other units. The most note worthy one being Dorothea, whose Meteor has huge range and who had a large amount of support options, meaning not only would she almost always provide the basic bonus, but the additional might that came with it. This allowed units to potentially always have the extra hit/avoid, which while not gamebreaking, was a huge asset on higher difficulties. Sadly, this was tweaked in later patches to balance it out.
• In Romance of the Three Kingdoms IV: Wall of Fire, one can transform a number of soldiers into a nigh-infinite number of soldiers by assigning them to a general's command and then declining to go to war, removing the general and reassigning him, and repeating as desired.
• In Xenonauts, if you leave an injured soldier in your base to recuperate, it will take many days. However, in earlier versions of the game, sending him or her into battle again and using a simple medikit would fix the problem instantly. This was eventually fixed before the final release.
• Advance Wars:
  • Much like the Fire Emblem glitch above, Advance Wars 2: Black Hole Rising had a means to take control of the enemy army through careful abuse of soft resets and the map maker. If you pulled it off, all you had to do was choose "Yield" from the options menu to win the match instantly, albeit at the cost of, hilariously enough, getting a 0 for "tactics" (the result of not destroying any enemy units).
  • And even moreso in the first Advance Wars, where it was possible to put the game in a glitched state where, in a nutshell, both the Campaign and the Map Editor were active at the exact same time. This allowed you to not win one, but every match by simply setting the "place unit" cursor to the color of the enemy army, and then choosing "yield" from the menu to instantly end their match before their turn even begins.
  • Advance Wars Dual Strike had a means of glitching the game to have no CO at all, resulting in a glitched "commander" who had Andy's theme, no CO power, and completely average stats with no unique abilities. Being able to choose no CO for your army would even become a feature in Advance Wars: Days of Ruin.
  • A less "glitchy" bug is the way the AI is coded to refuel units. The AI is indeed coded to move units adjacent to an APC to refuel them if they get low on fuel, but this is bugged because the AI is also coded to move transports last. This means they'll move their own units beside an APC, then the APC will move way, then the turn will end, and if left alone they'll effectively chase their own APCs about the map until they run dry on fuel. This actually makes Drake an incredibly useful CO on the Green Earth factory mission and the final missions of Advance Wars 2: Black Hole Rising: since his Super CO power drains half the fuel of his enemy, you can put a large swath of Hawke and Sturm's army into this glitched "chase the APC" behavior which renders them incredibly vulnerable to attack.
  • Reboot Camp has an infinite funds glitch on Version 1.0.0. All you need to do is drain your funds to exactly zero, exit the map, and reload the mission — your units will be built but you'll have the full amount of funds you would have received at the start of your turn, allowing you to build again. This can be repeated as many times as you like, so long as you can keep draining your money to zero.