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

• Accidental Aesop: BN4 of all games has the moral of "accept responsibility for your shortcomings instead of blaming them on others" thrown all over the place in filler tournament battles, and even the Big Bad, Dr. Regal, declines accountability in favor of deflecting blame onto the good guys and taking a Society Is to Blame stance at the end of the main plot. Despite this, it's never paid attention to outside of Lan being upset over operators blaming their Navis.
• Awesome Music: Both the final boss theme and especially the tournament battle theme are also considered to be some of the better parts of the game.
• Best Boss Ever: Dark MegaMan, which is a Mirror Match where the opponent has the exact same stats as you and will mimic your own strategies and attack patterns, which even includes program advances and Navi chips. Even players who admitted to not enjoying this game have expressed that this is one of the most challenging and exciting boss battles in the franchise.
• Broken Base: Defenders of the game's Fake Longevity-laden single player are few and far between, but the multiplayer is a slightly different story. Some feel that the game does a good job of clamping down on the Game-Breaker arms race that is Battle Network 3 multiplayer, while others feel that the Double Soul system is underdeveloped and that the lacking virus variety in single-player leads to an underwhelming chip library for multiplayer outside of a few standouts like the AirHockey and NumberBall series.
• Critical Dissonance: The games were given decent reviews (though noticeably lower than Battle Network 3), are the best-selling Battle Network entries, and the third highest selling overall Mega Man titles, but fans regard them as the worst games of the main series.
• Epileptic Trees: Due to having an unique design yet using a generic NetNavi for battles, it's generally believed that Tetsu was supposed to have a distinct Navi of his own (HardMan.exe being a popular guess), but the idea was dropped before release for whatever reason. There's no proof whatsoever of this being the case however, aside from the aforementioned circumstantial evidence.
• Game-Breaker:
  • Roll Soul's charge shot destroys the enemy's current Battle Chip. This doesn't do much in single-player, but is game-destroying in multiplayer as it removes your opponent's main form of...doing anything. Most unofficial tournaments ban it. Roll Soul still manages to be game-breaking in single-player thanks to its other benefit of restoring 10% max HP each time a chip is activated; unlike essentially every other chip-based Double Soul ability in the game, there are no restrictions whatsoever on the chips that trigger this ability. Chips of other elements, non-attacking chips, dimming chips, they all heal Roll Soul. Overall, this soul was bad enough that Battle Network 5's Recovery soul has nothing to do with recovery and is arguably the worst soul in that game, while Battle Network 6 revisits the concept with Spout Cross but only grants 5% and exclusively on Aqua chips at that.
  • Search Soul allows you to re-shuffle your chip selection (or "hand") up to 3 times per turn, you can even select some chips to keep and shuffle the rest. This makes it incredibly easy to access your best combos and Program Advances. It also boosts the Buster to fire five times with each charged shot, dealing at least 50 damage with the full burst, and auto-targets an enemy so you don't even need to be on the same row. Another one that's often banned in multiplayer.
  • The Air Hockey series of chips are easy to get and deal multiple fast, Break Element hits that can shred most enemies and even bosses.
  • One of the Japan-exclusive Mod Cards allows the player to throw a MegEnBom with Back + B, leading to effortless infinite combos.
  • Most of the Patch Cards in general are this. And with the Collection release giving access to the full library, for the first time outside of Japan as well, anyone can simply fine tune the less broken ones to give themselves a huge advantage, never mind going all in on the most powerful ones. Do mind the HP bugs on certain ones.
• Good Bad Bugs:
  • In Blue Moon, base ProtoMan's AI is flawed to the point that he stops doing anything if you steal his front column and stay in it. Later versions found in subsequent New Game Plus runs have more moves, though these, too, can be stopped with a mere two object chips.
  • Junk Soul's passive ability causes chips that were selected in previous turns to be "recycled", allowing them to be used again. This includes Dark Chips, which, if selected this way, can be activated without tainting MegaMan or permanently depleting his HP.
  • If Dark MegaMan loses all his HP on the same frame a poison panel depletes it, his HP is completely removed and all further damage does nothing to him, passive or direct. Damage is still registered if it's an attack, but it simply doesn't do anything. You’re still able to control him just fine, though.
  • Due to the way that the game checks for the "too many colors" Navi Customizer glitch, the player can use the Run command to save an illegal setup, return to the NaviCust, remove programs until there are four or less colors, exit the NaviCust without using Run, and no longer have to deal with the glitch. This also works in reverse if the player needs to carry a glitch for some reason; starting with a legal setup, stacking colors until there are more than four, then exiting without saving will inflict the glitch's effects onto MegaMan. Legacy Collection saves the color glitch in the same way as it does every other NaviCust glitch, eliminating this exploit.
• Good Bad Translation: While every game in the series has an English script of somewhat dubious quality, Battle Network 4's translation is the most messy. It's also really funny, with lines that are grammatically correct but super awkward ("We have become Masters of Science."), weird phrases it insists on using ("viruses busting") or sentences are just plain wrong ("What a polite young man she was."). As it's become one of the game's strange charm points to some of the fanbase, the Legacy Collection version keeps all of the flawed translations.
• Low-Tier Letdown:
  • Aqua Soul is considered utterly useless. It has a ridiculously weak basic charge shot, and its ability to charge Aqua chips for double damage isn't as useful as it sounds due to a lack of good options.
  • There's no reason to even ponder using Dark Chips outside of the fight that requires you to do so, between the incredibly lopsided benefits of Light karma and the multiple layers of penalties that trigger when a Dark Chip is activated.
• Memetic Mutation: Thanks to a rather humorous Let's Play by EPM, Duo's "Anger Impact◊" attack is often used to express anger at the game.
• Narm Charm: One of Duo's attacks produces a giant red face with an exaggerated angry expression that is too silly to be taken seriously. Regardless, fans consider it one of the most memorable elements of this game.
• The Scrappy:
  • Chisao gets kidnapped, and his kidnapper says he'll let him go provided Lan can find him and complete his challenges. Lan manages to find him shortly before his tournament match with Dex and GutsMan.EXE. After the tournament battle, Chisao admits he wasn't really kidnapped, and did this all to make Dex win by default to make his big brother look better. While Dex does get angry at Chisao's actions, Lan is willing to overlook this and forgive him for his motivation, and this didn't help improve the players' image of Chisao. It doesn't help that in the anime, he eventually displaced his brother while contributing very little to Lan's friend group dynamic.
  • Paulie, for being incredibly annoying, self-absorbed and risking the lives of his fellow villagers for the sake of Engineered Heroics, something that said villagers are more than willing to forgive him for and pretend nothing actually happened. In addition, his scenario (the one where a river management system is worshipped as a god) is considered among the most offensive in the series due to being rife with Unfortunate Implications regarding the game's Fantasy Counterpart Culture of Africa, with many players agreeing the game would be better off had it not existed.
  • Dr. Regal is very easy to despise not for his villainy but for being such a cartoonishly one-dimensional Card-Carrying Villain with nonsensical circular logic, obnoxious rants about how Humans Are Bastards, flimsy motivations that amount to nothing more than him doing things just For the Evulz, and acting very Stupid Evil to the point of bordering on Generic Doomsday Villain. He's easier to tolerate in the following games, though how much improvement was actually given to him is a matter of opinion that fans are split on.
• Scrappy Mechanic:
  • The semi-randomized nature of the game's story forces you to go into New Game Plus twice to get everything. This leads to a lot of Fake Longevity, due to repeating some scenarios during your second and third playthroughs to see the new ones.
  • Key items do not carry over between New Game Plus cycles. This becomes a problem when the C-Slider and Nebula Code both require significant Zenny investment to obtain, so you will need to sink money into those Cash Gates on every playthrough if you want the goodies locked behind them. To rub it in even further, the C-Slider even becomes mandatory for certain scenarios that require access to the Undernet.
  • Hunting down missed Blue/Purple Mystery Data from the fourth loop onward is made especially irritating by the game deciding to "helpfully" stock Mystery Data that has been accessed on three previous loops with Zenny and BugFrags, leaving the player to try to keep up with the Mystery Data that has actual unique items and the Mystery Data that is filler.
  • The Double Souls are generally considered a poor replacement for the Style Changes from the previous games. The inconsistency in initiating them (needing to sacrifice a chip that you can't set as your Regular chip) on top of the time limit restricts how one can utilize the Souls' abilities to their fullest.
• Sequelitis: Battle Network 4 sold very well after the success of Battle Network 3, but is widely regarded as an inferior entry and the lowest point of the franchise. There are some very obvious errors in the presentation (e.g. wrong character portraits), an incredibly sloppy translation, and the random scenarios lead to an unfocused story with a lot of Fake Longevity in the gameplay. While a few critics still gave the game high reviews, this is where the "rehash" complaints that would plague the rest of the Mega Man action RPGs really began to pick up, which only intensified for Battle Network 5 and Battle Network 6 in spite of being regarded as much better games by the fanbase.
• That One Attack: Upgraded versions of LaserMan have a laser attack that will disable NaviCust programs if it hits. The game doesn't telegraph this very well or inform you of what has been turned off, which can potentially be devastating if you rely on Under Shirt to survive lethal hits.
• That One Boss: Duo is seen as one of the hardest final bosses in the series, and a huge spike over most other fights in the game. He has many attacks that are extremely difficult to dodge, constantly destroys panels to limit your movement if you don't have Air Shoes, makes a number of powerful field-dependent chips useless since most of his side of the arena is just a void, and can only be damaged by hitting his moving core when it glows red. The core also has a wonky hitbox while simultaneously being the source of some attacks, making his tight vulnerability windows even harder to take advantage of. The game's own limited chip library and lackluster attacks also make it harder to go through Duo's HP, especially when you're expected to deplete 2000 of it with just first-tier chips and only three Souls on the first playthrough. And if you've been using Dark Chips to get through the game, Duo also disables your access to them, leaving you to fight him with a greatly reduced arsenal. No other enemy in the game does this.
• That One Level:
  • SparkMan's scenario locks you into a weak chip folder due to Lan's PET getting hacked, and you need to figure out the code to fix it. The code is randomized and the clues for it are hidden throughout several areas, forcing you to potentially engage in a lot of battles with the crappy folder.^note It's possible to brute force the code without clues via blind guesses since you're told which individual digits are correct and there are no penalties for trying. This leads to its own tedium, however, as it can take somewhere in the ballpark of 70 attempts until you stumble upon the correct code. This gets worse when you get the scenario in New Game Plus, as viruses have boosted stats while the hacked folder does not scale to compensate.
  • The carnival is full of puzzles based around riddles. The problem is that the game's English script is a "Blind Idiot" Translation bordering on a Translation Train Wreck, so the riddles are difficult to decipher and the answers make no sense.
  • Paulie's scenario. Not only do you have to deal with everything mentioned under The Scrappy, but you also have to deal with a Fetch Quest, another Fetch Quest that includes a quiz and virus gauntlet, and then the WaterGod Comp, a 16 room-long teleporter maze with many rooms featuring "dead Navis" that sic viruses on you, sometimes up to 4 or 5 battles in a row (and the network also has random encounters). And then fixing the river system requires another 5-stage virus battle. Making matters worse, this scenario is the only place to find the FullCust * chip, and you need to go out of your way inside the Water God to get it. This all makes Paulie even more hated. Oh, and this scenario isn't version-exclusive, so you're always at risk of seeing it.
  • MetalMan's scenario in Blue Moon starts with Tamako telling you to go visit her master on the Net before you can challenge her. Said master then drags you to a fetch quest for food AND drinks in the Park Area. Some might make a mistake of only bringing him the drink, since he only mentions getting him food when you talk to him the second time. Only then will he teach you the minigame portion of the scenario, which involves punching rocks with very precise timing. Depending on the rock's color, the gauge goes faster and faster every time. After that then Tamako challenges you to punch rocks under a strict time limit before you can Net Battle her in the tournament. Aside from the precision needed to break them, MetalMan can and will teleport freely to anywhere he wants, while you have to walk instead. And once he gets to the rock he wanted, you cannot interact with it and have to find another one nearby. Even worse, this part has 3 rounds you have to get through, each one putting more of the harder rocks, though at least there's a break between each round. The only saving grace of this scenario is the reward, which is one of the most broken Souls in the game.
• They Wasted a Perfectly Good Plot: The game features a literal Random Events Plot that is almost entirely disconnected from the Colony Drop and Dark Chip conspiracy premises. Only at the very end does it attempt to tie it all together, as Lan faces Duo, a being who judges humanity as evil, and must oppose him for the sake of everyone he's befriended around the world.
• Unexpected Character: The debut of ColdMan and BurnerMan confirmed that the Battle Network series was drawing from the Mega Man (Classic) Spin-Off Mega Man & Bass in earnest, which was unusual considering that the vast majority of NetNavis were either from the main series of classic games or Battle Network originals. There was, of course, the one-off appearance of MagicMan in the first game, but that version was altered from the original and stood alone for the whole original trilogy as Early-Installment Weirdness.
• Unintentionally Sympathetic: The Heel Navi who wants to delete the Mettaur Village is forced to be the Designated Villain. The scenario insists that the Mettaur are innocent; while the concept of benevolent viruses isn't unheard of (as shown with the Virus Breeder sidequest in 3, or even Match's scenario in Red Sun with a VolGear powering a hot dog stand), the vast majority of viruses are malevolent (which is why it's okay to bust them), so the Heel Navi is treated as a villain for simply suggesting to do his job. In a blatant attempt to force the issue, the Heel Navi spontaneously decides to attack MegaMan.
• Unintentionally Unsympathetic: Chisao fakes his own kidnapping to try to get Lan disqualified from a tournament as a no-show by distracting him. He's Easily Forgiven by the cast because he did it out of love for Dex, but it did not help his reputation as The Scrappy.

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