Awesome Moments: The final boss of the second game, the Valkyrie Tank. Aside from the fact that it's a full-fledged WWII supertank, the battlefield is a burning arms facility at the center of Lance's empire. The Valkyrie Tank itself has a giant cannon called the Omega Lazer, which comes with a devastating charged attack. There's at least four different kinds. The best part is that you fight against Lance himself, decked out in his Nazi uniform, looking as intimidating as a human final boss can be. The ONLY human final boss, so far.
DiVINe MaDNEss, the theme for the final boss of the third game. The music that plays when you fight the golem in the second qualifies as well. Both truly feel epic.
Heck, all three of the final boss themes in this series are, well, epic. The theme of the Valkyrie (the second game's final boss,) Organ Jaws, is especially awesome.
When you hear Fallen Blood, you know you are fighting nothing short of God.
Into Combat is great for pumping you up for the fourth game's boss fights.
With a theme as hardcore as Under My Skin, you know you're in for the fight of your life against your dark selves.
In Bullet Heaven specific music, there's Light in the Darkness of Destruction, the music that plays when fighting the bosses. Bullet Heaven 2 gets a remix of DiVINe MaDNEss AND Fallen Blood wrapped into one for the final boss, but the majestic organs in The Count of Darkness are awesome too.
TPF Trans does a very good job of letting you know that you're up against something unlike anything else in the game. Namely, the Godcat halves, the Glitch, and the Cosmic Monolith.
Complacent Gaming Syndrome: The upgrade system in the second game is designed to give you bonuses based on the moves you used the most since the last upgrade, so it's easy to fall into this.
In 3, the Clay enemies. They're each immune to numerous elements, come in large groups which are almost never all vulnerable to the same attacks, and one of the later ones can cast healing spells. They are, however, all vulnerable to Lance's bomb element attacks. Thankfully, 4 toned them down by a lot.
In 4, there are quite a few in the factory. The Satellite dishes can cause Siphon on all your party members, locking them from using skills. The Laser turrets charge for one turn, the next turn they fire a big laser that will more often than not kill a character. Fridge turrets will pull a wet-freeze combo, landing status effects irritatingly often, while the rest of the enemies whale on you, and since we're dealing with bruisers with a taste for lightning here, getting hit while frozen or wet will most certainly cut a good chunk of your lifebar. The Drill Golem enemies hurt like no tomorrow. Did we also mention that these three enemies have TONS of health and take a long time to kill? Oh, and the Defender from the first game comes back, and it is a bruiser. Suffice to say this is especially bad during the boss battle.
Mage Dogs heal and buff allies, drain your characters MP and generally come alongside some really tough enemies. They also fully resist Dark and Holy and have no real weaknesses. Thankfully, they are vulnerable to Syphon, which confines them to basic melee. Mage Birds are annoying for many of the same reasons. They have pretty much no offensive abilities, but just like Mage Dogs they heal and buff allies and steal your mana... and even worse, they also have a 50% resistance to Syphon. Thankfully, like many flyers, the Thunder element makes quick work of them.
The Jellies of Bullet Heaven. There's a specific orange type that produces a different type of homing bullet than the purple butterfly-wasps. Said bullet chases you... in staggered steps. It's a pain to dodge, and really hard to fool.
Ear Worm: The Rave v2 theme that is used for minigames in the third game. The other tracks are pretty catchy too.
Ensemble Darkhorse: NoLegs tends to be popular among the fans. People even ask if he's going to be a playable character. (Not just for the minigames.) He is playable in 3.3. He also finally becomes a party member of the upcoming 5.
Even Better Sequel: Every consecutive sequel. The first is just a plotless battle against wave after wave of enemies. The second is similar, but with more story. The third is a full-fledged RPG with a world map to explore, and the fourth is similar but with even more secrets and items, better mechanics, an additional character, a non-linear map, and more World Building.
The Tera Drill spell does ridiculous amounts of damage to enemies with defensive buffs. Buff attack on whoever has it and even Akron goes down relatively easily.
In the second game, getting Matt to learn Mana Leech. Almost any attack in which his sword makes contact with an enemy will give him between 110 and 130 mana for free. Legend, his strongest physical attack, only costs 90 mana. Throw in a few Counter abilities, and enemies will be actively feeding Matt mana points.
If Matt equips the Rune Blade in the fourth game, and forges it to the max level, AND if you give Matt most/all of the ham items to buff his attack, you can regularly attack enemies with skills that cost MP and more often than not, your MP will be filled up basically automatically. Also, the max level of the Rune Blade basically guarantees that Matt will syphon his targets, and makes him completely immune to be dispelled and syphoned himself. The Rune Blade also boosts the damage of holy skills. Not only that, but he's just about guaranteed to counter, and he may casts a powerful skill called Glitter regularly, which is again, boosted by the sword itself.
In Bullet Heaven 2, NoLegs has the Shooting Star sub-weapon. It fires continuously in place, lasts much longer than any non-toggleable weapon, and you can have several of them active at once (unlike the toggled weapons, where you can only have one at a time). By picking up a diamond or heart to recharge your weapon at the right time, you can end up firing nine streams of bullets at once counting your primary weapon. You can either scatter the Shooting Stars around around to hit everything onscreen or concentrate them in one spot to deal obscene damage - bosses can lose half their health within a second to the latter.
Goddamn Bats: The crows. They have high evasion and an accuracy-lowering attack. If all of your party gets debuffed, they'll take a lot longer to defeat.
There's also the robot fish in the factory in 4. They have a move that buffs their evasion, but the most annoying part is that when you kill them, they always release a missile attack that can cause stagger. The only way to avoid this is to kill them last/all at once and end the battle (or wave) so the missiles won't land.
Pretty much every Airborne Mook in the platformer spin-off, Adventure Story, but especially the flies. What makes them especially aggravating to deal with is all the backtracking you'll have to do after they knock you off a platform, or mess up your jump while you're in mid-air.
Growing the Beard: The first game, after you finish the slimes (which, unlike the other mooks, you have to get through four waves instead of two) and get to the first (mini?)boss, where then it becomes a challenge. The second game averts going through four rows of the basic enemy by throwing in a red bee.
In 3, the entire series evolves from a simple Turn-Based Combat-only RPG into a fully fledged one, with a world map!
Idiot Plot: In 4, Anna and others know how powerful the game's MacGuffins are. And yet no one stood guard of them. Considering they were stolen by the weakest enemies of the game, one must wonder if it was subtly Played for Laughs.
Also, if Anna didn't suspect Matt as the culprit entirely based on Fridge Logic, the original trio wouldn't have been dragged into the plot in the first place.
Mascot Mook: The Slimes, (or Slime Bunnies) and the legless cats.
More Popular Spin-off: Matt and Goku appeared in a early bunch of flash animation parodies. Matt himself is an Ensemble Darkhorse being a minor bit character that appears early on in one animation.
Nightmare Fuel: While mostly averted, there are a few points of the game that can be creepy. Goku has a visible spine sticking out, the move of the third game's final boss where the screen goes black to show some eyes and teeth with a Scare Chord, and speaking of screamers, Matt's screamer move...
Just Akron's move? How about Akron himself? In contrast with the majority of enemies that look either awesome or funny, that... THING looks downright nightmarish.
Godcat's Destroyer form. It's not enough that it's riding a giant skull that attacks using fleshy spear-tipped tentacles and bones, no. The sky goes dark, a cat statue in the background is crying tears of blood, and even further in the background you can see masses of tentacles, writhing back and forth.
The (optional) tombs in the fourth game's (also optional) graveyard are surprisingly dark for this game. There is no music, you first have to stumble around blindly to find a torch before you can see the entire room, and characters would very often comment on it, and the accesories you get are made of bone and have rather morbid effects. The left tomb is apparantly a sacrificial altar with... something disturbing on the ceiling. The actual graveyard itself? A lighthearted undead-themed area with little-to-nothing disturbing about it.
Fourth game: Matt is somewhat Oblivious to Love, which secretly disappoints Natz. It's explicitly shown that he returns her feelings to an extent, however.
Likewise in the fourth game, early on Lance tells Matt quietly that if he doesn't want Natz, Lance will take her for himself. Matt replies that Lance left her behind and split the party like a dumbass.
To throw in a little Les Yay on top of all that, Anna begins a conversation regarding Natz's breast size and it's applicability to combat. Natz cuts off the conversation quickly, noting Lance is quickly becoming a drooling pervert on the subject, while Matt is trying to avoid noticing the situation altogether. This is disappointing for Anna, who was about to ask to touch her breasts.
That One Attack: Cosmic Monoliths get one — To clarify, Every 3 rounds, they use an attack named Doomsday. It is a much stronger version of what the party can do by using Dark Runes, and it starts off with a weak beam trailed through the ground, dealing low damage to the party — THEN the actual attack kicks in, dealing MASSIVE damage to the party, capable of taking out anyone with no dark resistance, even at level 30. To top it off, Doomsday hits the entire field AND COSMIC MONOLITHS ABSORB DARK!? And it goes From Bad to Worse in the final medal area, where one of the battles is with all 3 monoliths. Combined, they're harder to kill than Akron himself. It is better to leave Cosmic for last in this case, as the other 2 monoliths do NOT absorb dark, and will be damaged by Doomsday — but since all 3 monoliths are incredibly powerful, it is so much more likely to kill you.
On top of all the instant death attacks in EBF 3, Doomsday counts too, and is a definite That One Attack; if you don't have sufficient dark resistance, you will die.
The sandworm is a notable offender: it can regenerate its tail, hit both players, poison both players, and its tail can stun. It is entirely possible to get poisoned, stunned, then attacked two turns in a row with poison doing additional damage, leading up to six attacks in a row. Your best hope is to use lots of healing items. Even better, get Black Fang out before the fight begins, then poison it with Unleash and Toxic and hold out until it dies. This gets lampshaded in the third game, in which an NPC notes how much trouble they were having against the sandworm; semi-ironically, the same game downgrades it to a relatively normal enemy.
Even for the final boss, Akron is very hard to beat. A Flunky Boss that summons Cosmic Monoliths and Skull Ghosts, the latter of which can pretty much cast whatever spell it wants. That includes an instant death spell. And two claws which can heal his already staggering seven hundred thousand HP, as well as giving every enemy on his side powerful status buffs and giving you debuffs and status effects. And a bunch of "Evil Worms" and "Evil Tails" that can give you all sorts of nasty status effects. He also switches his weaknesses and resistances around every couple turns, and as you damage him, he will occasionally go into his second form, where his attacks are even more powerful as well as gaining new ones, such as an area of effect chance of instant death attack, and he takes less damage until you knock him out of it.
The penultimate boss of the third game is annoyingly difficult too. You can't use any poisoning, holy, or dark all-targeted attacks because the healing head absorbs holy, and the dark/poison head absorbs dark and gains health from poison, which you can't remove. It's the only opponent in the entire game that also uses Regen, and it has an attack which damages you for about 1500 and heals each head by about 20,000. Chances are you're gonna die the first few times due to their massive hp and attack. At least it gets easier once you manage to defeat two of the heads, right? Nooooope. It turns into a Flunky Boss by frequently summoning four of the resident Demonic Spiders (or a Cosmic Monolith if the game really hates you). Save the holy head for last, and nothing dies. Save the dark/poison or blaze head for last, and you die.
Protector. It's a weapons platform that starts off with four minions: one uses fire, one electricity (this one can buff), one earth (including poison), and one holy (including healing, AND REGEN). It has 150,000-odd HP, when you're not even likely to be able to do 15,000 in a turn. Its attacks include a charged beam (that also debuffs you), which it likes to use if you buff yourself, and a gun that shoots a character two times, each for about 3000 damage (you're not likely to have over 6,000 HP yet), and multiple attacks which hit the entire party. If you have regen active, it'll use the particle beam to get rid of it. Not fun.
The Tundra Mammoth just deals an assload of damage, has friends that can heal him back to full health at will, AND a random ally walks in around the fourth round. Just run away if it's a Viking Monolith.
From the second game, the Guardian and the Zombie Hydra. The Guardian is a Wakeup Call Boss designed to teach you that you won't win this game without status effects, since he gets three vicious attacks per round unless you destroy his arms but has a move to restore and heal them unless you stick him with syphon or repeated stuns... except you have to break the arms first, which means several rounds of full-fledged attacking while getting pummeled before using a status ability which doesn't always work. The Hydra, meanwhile, is technically two enemies so he/they get(s) two attacks per round, both of which could be a One-Hit Kill move. And if you don't kill both heads on the same turn, the surviving head will heal the dead head. If you had them both nearly dead but accidentally killed one (say with a counter attack), you're likely to accidentally kill the other the same way before bringing it back down.
Even when considering its Wake-Up Call Boss status, the Praetorian has some horrid tendencies. Namely, its summons are the turrets mentioned up in the Demonic Spiders section, it has a charge attack that does some heavy damage to everyone, with a decent chance of an instant kill, and when it charges up it gets to slam you with the ion cannon, which hurts like hell, and has a big chance of stunning you for two turns. Oh, and it buffs itself to the 50% cap often, you'll need to dispel it regularly. Thankfully, you get a powerful summon for defeating it.
Rafflesia isn't exactly a walk in the park either. First, it starts the fight out with one of each of the four vine monsters as minions, including the healer vine and the water vine (plants, Rafflesia included, absorb water), and once you kill them, Rafflesia replaces them one at a time at the start of its every turn. Its most common attack is a leaf blade that has a good chance of inflicting Instant Death, and its second most common attack is a belch that cuts your attack and magic attack as low as it can go. In general, its difficult simply because it can quickly become an endurance match, and your resources may be limited depending on how many healing items you have.
That One Level: Kitten Ruins in the third game. Frustrating switch puzzle, confusing layout and one pain of a boss.
Dark Matt's Annihilate does a massive amount of damage, when the exact same Limit Break does next to no damage when used by Matt.
Possibly justified due to Matt's Annihilate having a higher chance to instantly kill compared to Dark Matt's.
Dark Natalie's Black Hole does not do damage to her, while when Natalie uses it the party takes a very small amount of damage with a chance of instantly dying. Note that Dark Natalie, like all bosses, is completely immune to instant death.
Dark Lance's Nuke does not burn him, while Lance's Nuke burns the whole party.
Unpopular Popular Character: Lance, especially going by his depiction in 4. While the main characters hate him, he's one of the fanbase's most popular party members. Some fan fiction works faze out most of his negative aspects entirely.
The second game. With a "giant mutant penis" (the sandworm is referred to as that in the scanbot entry) that vomits blood, you would think that it would get a higher rating than "Anyone" on Newgrounds. Even weirder because the original game was "Teen".
Early in the third installment, Matt says: "I used my fapping arm for that attack!" Also, innuendos of tentacle rape and the return of the giant mutant penis, all Played for Laughs.