Video Game / Mega Man Battle Network 4: Red Sun and Blue Moon

Spoilers for all Mega Man Battle Network entries preceding this one may have been left unmarked. You Have Been Warned!

Mega Man Battle Network 4 is a video game created by Capcom for the Game Boy Advance in 2003. It's the fourth installment in the Mega Man Battle Network series. There are two versions: Red Sun and Blue Moon.

Things have calmed down since WWW was defeated once again at the end of Battle Network 3, so Lan and MegaMan decide to partake in local NetBattle tournaments. However, evil is still on the loose, as a new organization called Nebula is causing chaos with their Dark Chips — powerful Battle Chips that corrupt the data of anyone that uses them. And while all this is going on, an asteroid makes its way towards Earth and threatens to destroy everything.

Battle Network 4 heralds a huge paradigm shift for the Battle Network series that would stick until the end of the franchise and separates the last three games from the first three. This is the first entry go all in with the multiple versions setup, which was present with Battle Network 3 but not fully utilized due to extenuating circumstances. The version differences are far more drastic than before, and there is more incentive to link games up thanks to some those differences being unlockable in the opposite version. Additionally, Battle Network 4 changes the series's art style to use slightly smaller and somewhat less detailed overworld sprites, further differentiating the second half of the series from its predecessors. Finally, it's the first game to use major one-time gimmicks to freshen things up.

The game's unique gimmick is its structure. The three tournaments Lan and MegaMan enter have semi-randomized opponents, with each Operator-Navi duo having their own small story scenario between matches. This makes each playthrough different and encourages entering New Game Plus (also unique to this game) twice to see everything and achieve 100% Completion.

Additionally, the big new gameplay mechanic in this entry is Double Soul, replacing Style Change. By sacrificing a Battle Chip, MegaMan takes on the abilities of another Navi he's resonated with for three turns. Double Soul replaces the MegaBuster's charge shot and provides other abilities, such as boosting damage for specific battle chips. There are six Double Souls in each version and only three can be obtained in the first run, making the mechanic the biggest motivator for replaying the game.

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This game provides examples of:

• Aesop Amnesia: The epilogue of Mega Man Battle Network 3 made a big deal about Heavy Sleeper Lan finally learning to wake up on time by himself, but this game starts with Lan being woken up by Mega Man once again.
• A.I. Breaker:
  • If ProtoMan is encountered on the first gameplay cycle, his main form of attack (other than a Counter-Attack) is Fighter Sword, which he will only use in the fourth column from the left. If you use an Area Grab to take that column, he will be left helpless for the rest of the match.
  • KendoMan is also known for having very flawed programming, even during his upgraded fights.
• Anti-Frustration Features:
  • There are a couple of instances where there are no penalties for using Dark Chips:
    • At one point in the story, the player is forced to use a Dark Chip to defeat ShadeMan.EXE, who is immune to everything else. All Dark Chip penalties are disabled in this event, as it would have otherwise applied more Maximum HP Reduction with every gameplay loop.
    • If one player is thrashing the other player a little too hard in a Link Battle, Dark Chips become a more proper Desperation Attack as Link Battles do not affect karma or maximum HP — but the Dark Chips will still apply their mid-combat debuffs!
  • A few self-contained comps keep low-level viruses even after the player starts a new loop of the game, allowing players to farm these viruses' lower-level chips.
  • Starting from this game, Delta Ray Edge's A button timing can be mashed out instead of needing to be frame-perfect as in Battle Network 3.
• Anti-Magic: Roll's arrows, whether from Roll herself, RoulSoul, or the Roll Arrow secret chips, break the opponent's BattleChips upon contact.
• Artificial Brilliance: The Mirror Match at the game's very end actually manages to mimic your behaviour fairly well - using Navi chips and even program advances against you.
• Artificial Stupidity: Enemy Navis on the first playthrough are slower, weaker, and in some cases use less attacks than they did in previous installments. ProtoMan in particular was downgraded severely from his previous Perfect Play A.I. strategy, leading to the AI Breaker listed above.
• Art-Shifted Sequel: This game's overworld uses smaller sprites and more saturated colors with the portraits more closely resembling the official art and the anime; this look carries over to the rest of the series. In battle, panels are drawn in a brighter, simpler style; on the other hand, MegaMan and enemies merely see subtle color tweaks.
• Ascended Extra:
  • For the first and only time in the series, generic Normal Navi and Heel Navi NPCs can be fought in Boss Battles.
  • Likewise with Roll.EXE, who has been a close companion of the heroes from the very first game, but had never been seen in an actual onscreen Net Battle until her appearance in the Eagle Tournament of Red Sun.
• Awesome, but Impractical:
  • Dark Chips are attacks equivalent to Program Advances in power that appear when the player is performing badly. If one uses them enough, MegaMan will gain access to them by default and certain Evil Chips will be usable. The problem is that the drawbacks far outweigh the benefits: you lose one hit point from your maximum every time you use one, status ailments are forced on you depending on the Dark Chips slotted in (even if you don't actually use them, like being forced to move forward constantly if you take the Dark Sword), you're unable to use Full Synchro, Soul Unisons and most Mega Chips, and the HubBatch becomes unavailable at the end of the Bonus Dungeon. Worse, Dark Chips are outright disabled against the difficult final boss for story reasons. In contrast, simply playing well and refusing the Dark Chips raises a chance to score double damage on any hit and, with good timing, keep gaining that bonus for every subsequent hit — a perk so powerful it was removed from the sequel.
  • One Patch Card changes MegaMan's default charge shot into WideShot3, a 100-damage attack that is unavoidable if used on the middle row of a clear field and can (unlike the generic charge shot) trigger counters. The issue is that it has a horrible charge rate, making it prone to being interrupted and near-useless for high busting ranks. Worse yet, the shot disappears as soon as it hits an enemy or obstacle, meaning that it's even more unwieldy on obstacle-heavy battlefields or when dealing with enemies that reside on separate columns.
  • Many Patch Cards that offer benefits which look too good to be true actually are, as they induce unlisted bugs with extreme drawbacks. Which Patch Cards are and aren't trapped in this way is wildly inconsistent.
• Balance Buff:
  • Guard is upgraded from a single-chip to a three-chip series, in exchange for Mettaurs losing their Shockwave chip series.
  • In Battle Network 3, Guts Style can activate Guts Machinegun by mashing the MegaBuster; it peppers the opponent with buster shots, but leaves MegaMan immobile and vulnerable to punishment. Guts Machinegun is inherited by Guts Soul in this game, except that MegaMan is now completely invincible while using it.
  • The Heat-V and Heat Side chips (alongside their Bubble counterparts) get increase in damage values as those chips were normally obtainable from New Game Plus exclusive second and third tier viruses.
• Bag of Spilling:
  • Lan and MegaMan once again start the game with effectively none of their battle-chips or upgrades carried over from previous installments of the series and nary an explanation to show for it.
  • The Navi Customizer is also not available initially until Lan's father gives it back to him after the first tournament, but that's because it was confiscated by Haruka after Lan got into trouble.
• "Blind Idiot" Translation: These games have the dubious honor of boasting more translation errors and typos than any other installment in the series. Even the text formatting in the dialogue boxes is awkward.
  • Heel Navis return from the original trilogy, their common name erroneously translated as "Heal" Navis. Even individual uses of the word "heel" are universally mistranslated as "heal".
  • The game also flat-out refuses to use the singular form of the word "virus", always using the pluralized "viruses" even when talking about individual ones. It seems as though somebody just ran a find-and-replace command on the whole localized script.
  • Haruka Hikari on Lilly, a priestess: "What a polite young man she was!"
  • "Mega Man, is the jack out now!"
  • "There are so many electronic store!"
  • "Leg's go, Mega Man!"
  • "Want to saver you progress?"
  • Many battlechips in the game have nonsensical and confusing descriptions, even accounting for the little space available for text.
  • The manual was also a mess.
• Bound and Gagged: Lan's doghouse alarm goes off and he rushes home to find his mother tied up and gagged on the floor in the corner of his room and warned him that they could easily do worse.
• The Bus Came Back: FireMan, NumberMan, and WoodMan return to the field of battle, operators in tow, for the first time since Mega Man Battle Network 1 (Mega Man Battle Chip Challenge notwithstanding); likewise ThunderMan and MetalMan from the second and third game, respectively.
• Brick Break: In Blue Moon, Tamako attempts this on a large rock (and hurts herself somewhat) to drive a point regarding "fighting spirit" with Lan, saying that it's proof Lan isn't ready to fight her yet because both of them knew they couldn't possibly break it with a punch, but only Tamako tried anyway. She will refer MegaMan to a Cyberworld fighting master who has him break three of them within a short time limit, then challenges him to three rounds of this against MetalMan before the tournament battle.
• Broken Aesop:
  • The player has the power to do this by deliberately using dark-chips, by corrupting MegaMan into his evil state, and especially by beating the game with MegaMan in that condition.
  • Multiple scenarios in the game touch on the same moral subject, but Lan and Mega will express opinions opposite to themselves depending on the scenario.
    • During the TopMan chapter, Lan discovers that NetBattling isn't merely "a game for the young" when they find out that their opponent is a senior citizen. In the ColdMan Scenario, however, Ivan Chillski calls NetBattling "just a game", which causes Lan to blow a gasket and threaten to physically attack him.
    • During the preliminaries of the first tournament, Lan and MegaMan discover a Hidden Mettaur Village is being threatened by a HeelNavi and defend it on the grounds that the viruses aren't doing anything wrong. During the FireMan scenario of the city tournament however, Lan and Mega will examine a malfunctioning grill, find a virus, and immediately delete it—and then, Mr. Match explains the virus was actually operating the grill and that viruses have their place, which Lan obstinately disagrees with.^note The unknown cause of the malfunction is not brought up.

• But Thou Must!: You're forced to use Dark Chips to defeat ShadeMan during his second fight, as he's immune to all other forms of damage.
• Call-Back:
  • Three of the five Evil Chips references the postgame area bosses from the previous three games; Anubis, Muramasa, and Black Wing representing PharaohMan, ShadowMan, and DarkMan, respectively.
  • The Lance Battle Chip debuting in Battle Network 2 is made into the Kilby virus family, an inversion of the "battle chip is made during or after the enemy's debut" standard in the series. Despite this, Lance is not obtained from Kilby viruses and they have their own Side Bamboo series instead.
• Cash Gate: Expect to shell out money for things like passcodes, C-Slider parts and chips with specific codes that cannot be obtained outside from chip dealers in order to progress through the story. Becomes very painful in the first playthrough, where the payouts from battles and Mystery Datas are ridiculously small compared to how much and how frequently the NPCs demand Zenny from the player.
• Clingy Macguffin: The Dark Chip dropped by ShadeMan. Lan and Mega ultimately choose to destroy it, provoking ShadeMan to try and kill them... and dark chips start becoming available in the ensuing fight.
• Comeback Mechanic: Two emotions can crop up in disadvantageous situations: Anxious or Angry. If MegaMan is unable to hit back for an extended period, he becomes Anxious, which causes Dark Chips to appear in the Custom Menu. Taking a massive amount of damage in a short amount of time or being paralyzed for more than a couple of seconds will lead to him being Angry, granting double damage and making him Immune to Flinching until his next chip attack.
• Continuity Drift: The Battle Network timeline is supposed to have diverged from the Mega Man (Classic) timeline when Tadashii Hikari went into networking instead of robotics. This game creates a Continuity Snarl through the Final Boss, an Alternate Self of Duo who is radically different from the Duo from the Classic timeline. This shouldn't be possible because Duo is from space, and thus beyond the reach of events occurring on Earth. The last two games took notice and gradually started shifting towards original characters and/or looking for inspiration from the X series.
• Continuity Nod: These games are saturated with throwbacks to earlier games in the series.
  • Lan's introduction directly mirrors his intro from the first game, up to and including having to collect his PET from across the room after Mega wakes him up.
  • The tutorial sequence has Lan jack MegaMan into an infected microwave, very much like the hacked oven from the FireMan scenario from the first game.
  • A handful of posters around ACDC Town feature images of Battle Network 3 characters, including Tadashii Hikari and Serenade.
  • During the BurnerMan scenario, he and FireMan get into a contest over which is the more Hot-Blooded that gets so out of hand that the entire internet is set ablaze, mirroring the FlameMan scenario from the third game; Lan's even gets the original water-gun program used in the hacked oven from the first game. (It's completely useless, however, and is soon replaced with something better)
  • The Hikari family's doghouse alarm system has usually featured a small local network that you could jack into for goodies; the alarm finally goes off during the events of the game.
• Cooking Duel: Against Flave Yamakawa in the normal-navi scenario of the national tournament.
• Crossover: with Boktai; Hideo Kojima himself cameos in Castillo late in the story, and MegaMan can meet Django and Otenko in the depths of the internet.
• Creator Cameo:
  • Masakazu Eguchi once again returns as Meijin Eguchi (Mr. Famous).
  • Mami, who hosts the national tournament, is directly adapted from the Real Life Battle Network tournament hostess of the same name.
• Dangerous Device Disposal Debacle: Lan and Mega happen upon a special dark chip left behind by ShadeMan, and learn from Higsby that it's an Artifact of Doom. The game forgets about it during the first tournament, only for it to come up again in the interlude before the second, when ShadeMan decides he wants it back. The boys successfully prevent him from retrieving it, but at the cost of the dark chip permanently infecting Mega Man, presumably because they simply said they should get rid of it several times before refusing to do so.
• Degraded Boss:
  • There are non-boss variants of the Heel Navi that have weaker battle-chips and a smaller number of hit-points compared to the boss variant.
  • The NaviShadow and NaviBlack are quicker, more aggressive variants of the NormalNavi and HeelNavi bosses, but with even fewer hit points than the most basic version of these Navi bosses.
• Demoted to Extra:
  • Mr. Match appears in BurnerMan's scenario in both games, but only competes in a tournament in Red Sun, reducing him to The Cameo in Blue Moon.
  • After Bass was given increasing levels of importance in the first three games, he is demoted back into being an optional Superboss in this game and keeps that status for the remainder of the series.
  • Magnum, PopUp (previously known as Mole), Cannonball, and MetaGel lose their respective virus families and are reduced to a single chip. Additionally, the Canodumb family is removed but all three of their BattleChips remain.
• Difficult, but Awesome: The "Counter" chip series strikes enemies without needing to aim, delivering a Counter Hit from anywhere on the battlefield for instant Full Synchro access. The quirks of Full Synchro also highlight the enemy's attacking frames to help you keep the chain of Counter Hits going, as well, so a folder built around Counter can destroy bosses with ease. The problem is finding the right moment to get the ball rolling, since Counter chips fizzle out when used at any other timing.
• Easter Egg:
  • Make sure to Always Check Behind the Chair, as there are seven Navi Codes for Mega Man Battle Chip Challenge that will unlock boss fights for the latter game.
  • During the ProtoMan scenario, if you attempt to escape combat by pressing L, instead of the usual dialogue, MegaMan will instead give Chaud encouragement.
  • Certain battle-chips have secret "command codes", special input-strings that will give the battle-chip an extra effect when entered correctly on using the chip. Variable Sword is the most prominently known example since it has several different ones, but there are half a dozen Navi chips that have command codes as well.
• Evil Counterpart:
  • Dark chips appear as darkened versions of bog-standard battle-chips that offer Power at a Price—they do damage that rivals a Program Advance, but selecting them for battle will riddle the user with bugs.
  • Heel Navis are, as always, the Heel counterparts to Normal Navis.
  • The Final Boss of the game extracts MegaMan's own Dark Soul from his body and challenges him to a Mirror Match. The Mirror of Truth in the depths of Black Earth does the same.
  • NaviShadow and NaviBlack enemies are Normal Navis and Heel Navis that have fully succumbed to The Corruption.
  • The second area of Black Earth challenges the player to fight a gauntlet of DS Navis, copies of MegaMan's six Double Soul Navis that also have the powers of MegaMan's Dark Soul.
• Excuse Plot: The majority of the game follows Lan and MegaMan as they participate in a series of tournaments, meeting quirky characters and helping them solve their own problems along the way. While there are two main sources of conflict in the form of an impending asteroid collision and the shady Nebula organization, the main duo have very little input in either storyline, as they only get involved in the former at the very end of the game, and only actively combat Nebula during short scenarios in between tournaments.
• Fake Longevity: In theory, the New Game Plus system sounds like an excellent way to extend the life of the game without becoming too dull. In practice, it quickly becomes obvious that it was designed to mask the fact that this game does not have as much unique single-player content as its predecessors:
  • The first playthrough only has base-level viruses so, outside of chips grabbed from other sources, the player is stuck with the weakest tier of chips. The second playthrough upgrades the viruses in most areas to their V2 incarnations, while the third and beyond use their V3 incarnations.
  • There are multiple Fetch Quests that have to be done on every single playthrough, such as assembling the C-Slider and the qualifiers for the second tournament.
  • Each tournament has two possible generic Navi scenarios, two possible unique Navi scenarios, and two possible Double Soul Navi scenarios, with the game selecting one from each category to create a three-round path to the championship. With this setup, it would be theoretically possible to see everything in two playthroughs. Except Capcom needed to justify the third playthrough beyond having V3 viruses, so the second playthrough is guaranteed to have repeats, including at least one Navi that has already given the player their Double Soul.
  • While the international tournament introduces some variety in the areas that the player visits, the first two tournaments' scenarios largely consists of sending the player to the same handful of places with different gimmicks attached. The second quarter of the game in particular absolutely loves sending you to the end of Park Area 3; even with the best possible luck, you'll still need to go there multiple times for arbitrary reasons.
  • Blue Mystery Data and Purple Mystery Data are already tricky to deal with, but this game adds an extra wrinkle by respawning them with new items for the second and third playthroughs. What happens if you miss a Blue or Purple Mystery Data and start a new loop of the game, you might ask? That particular Mystery Data stays on the same "tier" until it is picked up, and doesn't refresh until a new playthrough is started. In short, if you miss Mystery Data relevant to 100% Completion, you get to tack on a fourth and maybe even fifth or sixth playthrough.
• Fight Woosh: In addition to the standard "fade to white" effect, tournament battles use a unique effect where green lines move across a dark screen, forming silhouettes of the participating Navis and the battle grid before flashing to reveal the standard battle view.
• Food as Characterization: Exaggerated with the takoyaki saleswoman (the hot dog lady in English) stationed outside the Dendome, who has a takoyaki emblem on her shirt and whose ponytail is also takoyaki-shaped.
• Game-Breaking Bug:
  • The AquaMan and GutsMan Navi chips and the Park Area explored during WoodMan's scenario cause horrible loading slowdowns when played on emulators or an original model DS. The Park Area version of the issue is particularly onerous, since it can occur when leaving a random encounter or even saving the game. Technically the game has not broken; it "simply" temporarily freezes for as long as 20 minutes and will run normally afterward until you're forced to trigger another slowdown. Thankfully, this was fixed for the DS Lite, patches and AR codes have been developed by fans, and the emulators mGBA and NO$GBA have managed to finally solve the issue.
  • The Free Space battle board. If you link up with the other version before you have all six of the double souls (this means a New Game Plus Plus at the very minimum) then your game will crash and corrupt the game's code. And by that we mean that it carries a high chance to permanently break it!
  • When Dr. Regal attempts suicide at the end, there's a dramatic slowdown when Lan and Chaud try to reach out for him. If the player skips the cutscene at this point in the Japanese version, the slowdown will carry over to the credits.
  • Downplayed in the first Japanese release with regards to the ShadeManDS chip: instead of ShadeMan dropping ShadeManDS X when defeated while MegaMan is in Evil state, he drops ShadeManDS S — which doesn't exist, so the player gets nothing. This is a consequence of ShadeMan being one of the few NaviChip series that does not have a chip code based on their source Navi's (Japanese) name.
• Gameplay and Story Segregation: Corrupting MegaMan with Dark Chips to the point he goes evil in the battle interface has no effect whatsoever in the plot.
• Gatling Good: This game introduces the Vulcan series, simple gatling guns that hit multiple times for 10 HP each.
• Gold-Colored Superiority: Duo Omega is unique among the powered-up final bosses in that he gets a Palette Swap signifying his status. The primary color is, of course, gold.
• Good Bad Bugs: The timer until the next random encounter is reset whenever the game enters a menu such as to save, making it possible to completely negate random encounters. Exceptionally useful for avoiding the Demonic Spiders in Black Earth 2, which don't drop anything and can only be harmed by swords.
• Guide Dang It!:
  • The Version-Exclusive Content combined with the RNG of the tournament brackets leads to a hiccup: Red Sun completely lacks a scenario to grant access to YumLand's overworld early, and Blue Moon only has one scenario that grants early access to Sharo's overworld. These overworlds are quietly opened up in the endgame, which is a problem when the player has to travel to areas they may not know exist.
  • The Meteor Computer has a gimmick where a cutscene will play at random intervals, showing MegaMan being sucked into a black hole and warped back to the entrance, effectively undoing all progress. What the game does not tell the player is that they are supposed to mash the A button whenever the cutscene is triggered, as doing so will enable MegaMan to swim back down to the floor, resisting the gravitational pull. If the player fails to realize this mechanic through experimentation or with the help of a guide, the final level can be rendered almost unwinnable.
  • Some self-contained computers also have second tier viruses which would provide useful chips for the first run, but they are very rare encounters.
  • Many of this game's Patch Cards inflict glitches onto MegaMan, but none of them are listed on the actual cards. Outside of looking at a guide, players must go through trial-and-error to determine which combination of buffs and debuffs works for them. This is enforced in Legacy Collection, which opts to directly translate the card descriptions and only gives additional context if the original cards lacked a description or the cards are banned from online play.
• Hand in the Hole: In order to prove that he's a contestant in the last tournament of the story, Lan has to put his hand in the mouth of a stone lion face. It threatened to bite his hand off if he wasn't who he said he was. It's actually a DNA tester.
• Hard Mode Mooks: The game only permits you to fight first-tier enemies on the first go-round, and as a result, you only get first-tier chips for the duration of the run. On a New Game Plus, though, the enemies are upgraded to second tier, moving faster and hitting harder and yielding stronger chips. Some even have additional effects to their attacks. Go on yet another new game plus run after that, and the enemies will reach their third and strongest tier. Each virus tier has an EX tier added, which are slightly stronger but have the same chip yield. Because of the scaling system, this makes second tier viruses practically third tier, and third tier viruses fifth.
• Hero Ball: Lan holds it. He'd win over half of his tournament battles by default if he simply just stayed out of his opponents' lives.
• Hopeless Boss Fight: Downplayed. In his first two fights, ShadeMan.EXE won't take conventional damage, but the first battle will end when MegaMan lands enough hits on him anyway, and the second will end when MegaMan uses Dark Chips on him.
• Horse of a Different Color: The NetFrica village Lan goes to shows that ostriches become the primary transportation with no commentary attached.
• Inevitable Tournament: This game consists almost entirely of three major tournaments (the closest things the games have to story are treated as B and C plots). The game hits you with a New Game Plus that requires you to compete in all three all over again. (If you want to achieve absolutely everything, there are four cycles of the same story for you to pass through).
• Intercontinuity Crossover: Battle Network 4 had minor crossover content with Mega Man Zero 3, a game from another branch of the franchise timeline. Battle Network players could obtain the rare Z-Saver battle-chip from Zero 3 cartridges, but the fact that Z-Sabers were mainly limited to one per Zero 3 cartridge led many to understand this was Permanently Missable Content—and then, eighteen years after release, someone discovered a never-before-seen code to obtain Z-Saver chips from the Number Trader.
• Interface Screw: During the VideoMan scenario, MegaMan gets "rewound" and has his controls reversed. You then have to traverse parts of the Net in this state to find items while avoiding obstacles that force you to restart when touched.
• Jerkass: Some of Lan's tournament opponents in 4. Even if they aren't, someone will always cause a mess before the match and dragging Lan and MegaMan into their problem, sometimes on purpose.
• Karma Houdini: Almost every single opponent you fight that commits a crime seems to get off the hook one way or another. Take Ivan Chillski, for example, the self-absorbed prat who hacked government satellites in his own country to cause a blizzard in another (Capcom Science is very, very soft) for the sake of his own personal comfort; now, he gets arrested for this, and even gets a personal interrogation room in Netfrica for it, but is somehow freed and returned to his own country in time to make an appearance for the finale. Or take Paulie, from Netfrica, who nearly caused his village to die of thirst out of childish spite, and yet Lan personally asks for him to be forgiven when punishment looms its head.
• Karma Meter: MegaMan's palette darkens or brightens depending on whether he uses or abstains from using Dark Chips, respectively. MegaMan's rating on the karma meter determines both the abilities, programs, and battle-chips he can use and his emotional stability.
• Knight of Cerebus: When you first see ShadeMan, he's just floating in a corner, being creepy and creaking to himself, but once you leave and come back, people are screaming, Navis are lying dead all over the network (not deleted, dead: limp, motionless, and unresponding), and now that he's speaking in sentences, he tells you with perfect manners that he's off to find a nice lady Navi for dessert. He finds Roll.
• Last Lousy Point:
  • The preliminaries of the nationwide tournament require Lan and MegaMan to require a number of points from all over the available areas at the time. While many are available in large batches, individual points will be in obscure locations, so without a Guide players may struggle immensely to get the total required number.
  • There are no less than four cycles of the game, and specific battle-chips and HP Memories are distributed through each. These goodies are locked to their specific location and gameplay cycle, so if you miss one when you beat that cycle of the game, it won't technically be Permanently Missable Content, but the player must start and beat the game three more times to restart that particular cycle.
• The Law of Conservation of Detail:
  • Averted with NormalNavis and HeelNavis, who are universally NPCs in other games but are actually fought in combat in this game.
  • This game's revised layout for ACDC Town completely omits ACDC Elementary, since none of the game's adventures involve school.
• Let's Meet the Meat: From ElecTown: "It's a sign of a cow recommending you eat beef...But what cow in their right mind would say that?!"
• Light 'em Up: Gun del Sol, the signature weapon of the Boktai franchise, sprays a column with light that rapidly drains enemies' HP.
• Loners Are Freaks: The use of Dark Chips and Evil MegaMan prevents the use of Double Souls in favor of raw individual power.
• Loophole Abuse: Accumulating enough dark karma to naturally wield Evil Chips prevents the player from activating Double Souls during battle...unless the player forces MegaMan into a Soul via Patch Cards, in which case MegaMan gets the benefits of the Soul while retaining the ability to freely wield Evil and Dark Chips.
• Magikarp Power: The Red Sun and Blue Moon Giga Chips are pretty weak when compared to other Gigas (Red Sun doing 300 damage only if all 5 hits connect ^note down to 100 if only the final attack lands, and Blue Moon doing 200), but they have a hidden feature that increases their damage output the more Network Battles you win against someone playing the opposite version. A full-power Red Sun deals 700 damage (the first four hits still deal 50 damage apiece, but the final hit powers up to 500 damage), while a full-power Blue Moon deals 600 damage.
• Mythology Gag: LaserMan's "Prepare to become space dust!" pre-fight dialogue is taken from a quote used by Sigma in Mega Man X4.
• Nerf:
  • The max Custom Screen size has been reduced from 10 chips to 8. The 10-chip selection still exists as a perk exclusive to Number Soul, but that comes with the drawbacks and limitations of the Double Soul system and is also Version-Exclusive Content. Futhermore, the ADD function is completely removed, meaning that the player can't expand their chip selection on the fly beyond what souls such as the aforementioned Number Soul offer.
  • It is now impossible to steal any panels from the opponent's back-most column, unlike previous games where combatants can be locked to a single panel.
  • In the first three games, each chip has up to five letter codes plus the wildcard that can be assigned to them. Starting with this game, chips only have up to three letter codes plus the wildcard, making Folder synergy more challenging.
  • As part of the overhaul to the countering system, the vanilla MegaBuster can no longer be used to counter, unlike in Battle Network 3.
  • The Zeta Cannon PA has been replaced by the much weaker Giga Cannon. Giga Cannon doesn't provide temporary invincibility like its predecessor, and only fires a single shot instead of allowing multiple ones.
  • The Variable Sword command that allows the player to fire Sword Beams only fires one, as opposed to three in previous games. What's more, the elemental variant which fired four sword attacks is removed entirely.
  • The Hub Batch program has been expanded from a 3x3 square to a clunky bulky mass that takes up your whole command line and leaves little room for more.
• New Game Plus: Once you've beaten the game, you can restart the story with your money, Double Souls, and some of your items carrying over. The game will re-roll the random tournament scenarios to make sure you get some new ones, upgrade the viruses and bosses, and replace the contents of Mystery Data you've collected with new drops.
• No Fair Cheating: S-Rank victories against Omega Navis are not recorded if the player is using one or more Patch Cards, preventing the player from using them for the sake of raising the attack power of SP NaviChips. On the flip side, the player can only encounter BassXX if they have Patch Cards activated.
• Nostalgia Level: Undernet 6 is Undernet 2 from Mega Man Battle Network 2 with a recolor.
• Not the Intended Use: The new Blinder battle-chip not only induces the blind Status Effect, it negates Mercy Invincibility, making it a favorite for shaving down time on S-Ranking enemies.
• Obvious Rule Patch:
  • This game introduces what is commonly known as "Time Freeze Counter": if a "dimming" chip (which stops time and thus is typically easy to use) is activated by one player and the opposite player has their own dimming chip loaded, the opposite player can trigger their chip before the first player's chip fully activates. This mechanic coincides with Invis becoming a dimming chip, effectively creating a check for both. Furthermore, numerous support effects are incompatible with dimming chips.
  • "All Guard", a pair of Purposely Overpowered Patch Cards that make the player immune to everything except Break and draining damage, are outright banned in Legacy Collection's online battles.
• Oddball in the Series: Battle Network 4 is quite different from both its predecessors and successors in several regards.
  • The story is semi-randomized due to the tournament structure, and the scenarios you experience based on what opponent you're up against don't really coalesce into a cohesive narrative. The fact that possible opponents will be eliminated before you encounter them also means a large amount of content is locked out of the initial playthrough. You have to go through New Game Plus twice to see everything and then unlock the true postgame (typically reserved for Endgame+ in other Battle Network games), and said NG+ feature is only present in this entry.
  • This game, the first to include chip elements beyond Fire, Aqua, Elec, and Wood, is the only one to have Panel-Cracking as an element; Battle Network 5 replaces it with Cursor (and changed SearchSoul's type in the process), while Battle Network 6 only retains Sword, Wind, Cursor, and Breaking.
  • Roll's NaviChips are typically given to you for free at set points in the story. Since she's a boss fight here and Version-Exclusive Content on top of that, her chips are earned like any other NaviChip in this entry only.
  • This game features the only Navi Customizer theme that is not a remix of the Battle Network 3 NaviCust theme, and is also the only game not to use a remix of its main theme as a dungeon BGM. Battle Network 4's music in general sticks out relative to the rest of the main series, with wildly different instruments used in its BGM.
  • This is the only installment that lacks a stationary turret virus, one of the basic recurring virus types alongside the Mettaur. The first three games had the Canodumb while 5 and 6 put their own spin on the concept with the CanGuard and Gunner, respectively. Spikeys and Larks serve as the closest replacements for the Canodumbs here.
  • Generic Navis and Heel Navis are fought directly instead of them throwing viruses at you.
  • There are only three "dungeons" (computers with multiple areas ending in a boss) in the game, the first two ending with a battle against ShadeMan and the last ending with the final boss. Worse, both versions of the ShadeMan fight are an interactive Cutscene Boss, meaning only one dungeon has a legitimate boss fight at the end. Other Battle Network games have no less than four dungeons and, Boss Rushes aside, never repeat end bosses.
  • This is the first and only game since the original Battle Network to lack a series of Pop Quiz minigames.
• One-Steve Limit: The recurring Repair chip (which restores panels to its default condition) is renamed into Panel Return with the introduction of another chip named Repair (which restores the durability of obstacles).
• Outside-Context Problem: The main threat looming over the world for the entire game is am asteroid on a crash course with Earth. Said asteroid is artificial and of alien origin, with the program running it designed to wipe out planets it deems to have too much evil.
• Oxygen Meter: Used during AquaMan's chapter in Blue Moon, when looking for him in the flooded net. This is refilled by stepping into a homepage.
• Power Nullifier:
  • In Player Versus Player, LaserMan SP can (via secret inputs) reduce the opponent's Buster stats to minimum values, remove their non-Buster/HP NaviCust programs, reduce their Custom selection by one chip, or disable their Patch Cards.
  • Signal Red prevents the opponent from using BattleChips while the signal is red. When the signal is blue, it instead blinds the opponent.
• Pragmatic Adaptation: The Boktai series' signature gimmick is that the player benefits for exposing the game cartridge to direct sunlight. Since Mega Man Battle Network 4 obviously doesn't have a solar sensor built in, the gimmick is represented by increasing the Gun del Sol chips' HP-sapping effect whenever Lan is jacked in from an outdoor location.
• Random Events Plot: The game's scenarios are determined randomly by the tournament system and have no established chronological arrangement. Many of them have no bearing on the main plot and are nonsensical, requiring Lan and MegaMan to do things such as exorcise a handful of troublemaking ghost Navis, take part in an Iron Chef parody cook-off, or play a few rounds of free kicks in soccer with heavy explosives as the ball.
• Restored My Faith in Humanity: Duo, a Planet Destroying Judge, Jury, and Executioner, seeks to wipe out mankind because it's wicked but changes after his fight with MegaMan.
• Remixed Level: Several stages that would be unique in other installments of the series instead take place on Park Area, with just the set of obstacles changing with each scenario.
• Revenue-Enhancing Devices:
  • This game introduces "Patch Cards", Japan-exclusive cards that are activated through the Game Boy Advance's e-Reader peripheral and grant various effects such as changing the Buster and allowing permanent Soul usage. The cards never released overseas, but the system is fully translated and can be activated in the international versions via cheats. The Legacy Collection port lets the player access them in all versions of the game with no extra purchases required.
  • Capcom also produced the Battle Chip Gate, another Japan-exclusive accessory that can detect toy BattleChips and feed their data into the GBA. The presence of this peripheral unlocks a mode where Navis are AI controlled and only respond to real-world BattleChips, being a Poorly Disguised Pilot for Rockman.EXE 4.5: Real Operation.
• Sequel Escalation:
  • Battle Network 3 has one prominent Tournament Arc, with the buildup and tournament itself taking up the first half of the game. This game has three tournaments that take up nearly the entirety of the game.
  • Inverted with this game's GigaChip selection. In Battle Network 3, almost every NaviChip has five versions, with the V5 chips being GigaChips. This game consolidates these NaviChip levels by giving SP NaviChips variable attack power, resulting in the GigaChip selection being reduced to the five version-exclusives and the promotional Duo chip.
• Socialization Bonus: While Double Souls remain Version-Exclusive Content, the Navis that give them can be sent to players with the opposite version of the game. This opens up Free Tournament, which allows the latter player to obtain BattleChips exclusive to that mode and potentially trade them back to the person who gave them the Navi in the first place. For example, only Red Sun has access to Roll Soul and Roll's NaviChips, but only a Blue Moon player with Roll's Navi data has access to the Roll Arrow series, meaning that a Red Sun player who wants Roll Arrow will have to interact with a Blue Moon player.
• Spell My Name With An S: As a result of the shoddy translation, the antagonistic Heel Navis (as in a wrestling heel, i.e. a villain) are now called Heal Navis.
• Status-Buff Dispel: The Blue Moon Giga Chip nullifies all of an opponent's NaviCust programs, with the exception of stat boosts, when used in a Network Battle.
• Strong Enemies, Low Rewards: Because second and third-tier viruses are reserved for the New Game Plus, the game introduces the EX tier for viruses, which are stronger but yields the same chip rewards as their lower-tier counterparts. It is carried over to Battle Network 5, and phased out in Battle Network 6.
• Suspiciously Similar Substitute:
  • The four souls representing the primary elements (Fire, Aqua, Thunder, and Wood) are moreso expansions of the elemental bonuses given by the Style Change system of Battle Network 2 and Battle Network 3 than they are adaptations of their source Navis. This is especially blatant with Wood Soul, as it retains Wood Style's Twister charge shot despite the fact that WoodMan has nothing resembling it in his arsenal.
  • JunkMan's chip is Poltergeist from Battle Network 2 and Battle Network 3 in everything but name.
• Temporary Blindness: This game introduces Blind as a Status Effect, which causes all enemies to disappear from view when inflicted on a player and causes the AI to randomly guess the player's position when inflicted on a virus or boss. The aptly-named Blinder BattleChip inflicts this, as does a newly-introduced variation of the Trumpy virus and its BattleChip Silence.
• Thermal Dissident: Ivan, who comes from the Fantasy Counterpart Culture to Russia, finds the European-counterpart too hot, but that might be due to him never taking off his coat.
• Title Drop: The global tournament, NAXA's laser, and the premiere giga chip of each game all share their name with the version title.
• Took a Level in Badass: You could end up facing Roll in the Electopia tournament (the second tournament). By comparison, in the previous game, she had failed the last round of the N1 Grand Prix preliminaries and didn't even make the tournament proper. She makes use of what's stated to be her previously-existing speed, as well as a newly acquired (during the events of that game, even!) virus-taming and summoning ability. It's also the first time you get to fight her.
• Trailers Always Spoil: Not that they tried to keep the Big Bad much of a secret, but this trailer still doesn't help things.
• Traveling at the Speed of Plot:
  • Once you are given access to airplane travel, suddenly traveling to countries around the world is done almost instantly. While it is convenient for gameplay purposes, it causes some logical issues when strict time limit is concerned, most notably during the KendoMan scenario. Lan asks permission to delay their match for what is assumed to be a short time period so that he can bring back Mr. Famous, who is being held hostage in Netfrica. Electopia and Netopia are relatively closer, yet it takes half a day to travel by plane in the second game.
  • The asteroid is ridiculously fast for something that is supposed to be around Pluto in the intro. It only took it around a month tops to reach Earth, meaning it has to be moving at a little less than 3 million meters per second.
• Undead Counterpart:
  • Navi "ghosts", powerful phantom duplicates of custom Navis that the player defeats over the course of the story, can be found lingering around the internet in specific locations or as Random Encounters.
  • The NaviShadow and NaviBlack enemies saturating the Black Earth Bonus Dungeon are wraithlike Evil Counterparts of Normal Navis and Heel Navis who were overtaken by The Corruption.
• The Unfought: It is actually impossible to face the base version of FireMan in Red Sun and NumberMan in Blue Moon, as the games are programmed to always have GutsMan and AquaMan respectively become the player's first Double Soul.
• Version-Exclusive Content:
  • Each game features six unique Navis for MegaMan to enter Double Soul with, along with their operators, unique scenarios, battle-chips, and Random Encounters with more powerful versions. In certain cases, this even determines when Lan and Mega can get access to various regions of the map.
  • Each version has a unique set of Giga-class battle-chips, like Mega Man Battle Network 3: White and Blue before them.
  • The names of the citywide, national, and global tournaments are different in each version.
• Video Game Cruelty Punishment: Battle Network 4 treats using Dark Chips on your Navi as the equivalent of giving drugs to your own child, but there is nothing preventing the player from abusing their powerful effects in battle. However, MegaMan loses the ability to use Dark Chips just before the final boss. As a result, if the players had been relying on them for the entire game, they will be forced to tackle the last battle with a crippled HP, no access to Full Synchro or Soul Unisons and no attacks other than the basic buster and chips on the main folder.
• What Happened to the Mouse?: During the endgame, Dr. Regal explains that two tournaments (named after the game versions) were held to determine who would best be suited to help with the asteroid problem. Lan and MegaMan win one of the tournaments, but the winners of the other tournament are never revealed.
• Writing Around Trademarks: The group of scientists keeping tabs on the asteroid situation are called NAXA (ANSA in the original Japanese script), a clear riff on the real life NASA and JAXA space agencies from the U.S. and Japan, respectively.

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