Recca, the Ur Example. On NES. It goes even more hellish in the Zanki Attack mode, where enemies explode into four or so suicide bullets when destroyed, especially when they come in waves of ten to twenty. The main difference between Recca and most of the examples in this page, is that the bullets fill the screen ANDthey are absurdly fast.
Batsugun, one of Toaplan's last games before they closed in 1994, is the Trope Maker. In fact, several members of Toaplan formed these companies after their closure: Cave (formed from the Batsugun team), 8ing/Raizing, Takumi, and Gazelle.
Almost anything ever produced by Cave, including DonPachi, DoDonPachi (the Trope Codifier) and especially later sequels, culminating in DoDonPachi Daifukkatsu. Cave shooters typically have two loops. The first loop will look feasibly beatable. To get to the second, you usually have to not die and not use more than a couple of bombs (or some variation on that). The second loop will be No One Could Survive That. At the end or after the end of the second loop (depending on the game), you finally go up against the True Final Boss who makes the entire rest of the game look like a cakewalk. And naturally, in most of these games, you have to beat the true boss to even see the "good" ending.
Ketsui, and its DS Boss Rush port, Ketsui Death Label have bullets that will curve, multiply, pause, and perform all sorts of other behavior, as if they're organic bullets. Death Label is perhaps notable for being one of the first danmaku games to grace a portable system, something that one YouTube user describes as "bullet hell in your pocket."
The Touhou games are perhaps the best known example of Bullet Hell these days. The above picture is a screenshot from the battle with Yukari Yakumo, the secondBonus Boss of Perfect Cherry Blossom, who is unleashing her infamous "Boundary of Life and Death" spell card attack (which is an upgraded version of the final attack belonging to the normalBonus Boss, Ran Yakumo), in which she fires nigh every kind of bullet in the game. Just when you think that card's the end of it, there's still one more to live through.
Even worse in that Yukari is generally considered one of the easier bonus bosses, especially compared to the likes of Flandre or Koishi.
There's also Touhou Danmakufu which allows you to create your own Touhou-style danmaku games, including bosses with custom-made spellcards.
All of Raizing/Eighting games before they moved to fighting games.
Battle Garegga, where the realistic bullets blend with the background, making the game seem harder than it really is.
Their entry on Capcom's 1940 series, 1944: The Loop Master.
Cho Ren Sha 68k has danmaku elements.
Blast Works, which includes a bullet pattern editor in case the game is too easy for you.
Blast Works is the Adaptation Distillation of Tumiki Fighters, a previous shmup by Kenta Cho, who worked on other freeware Bullet Hell games such as Noiz2sa, rRootage, Parsec47, and Torus Trooper. In fact, he developed an XML-based markup language called BulletML, an open-source markup language that lets you develop your own Bullet Hell patterns.
And again in the sequel with Bizarre Jelly 5. Notable for its special difficulty, unlocked after clearing hard without losing a life. Reaching the end of this mode results in a Bonus Boss fight against the Glastonbury. While tough on its own, it unleashes Bullet Hell upon reaching its last breath. Did we mention that you can't continue in this mode after losing your three lives?
In Ikaruga you can (and usually have to) absorb some bullets (due to the polarity system). The clouds of bullets that get shot your way often have no spaces between them whatsoever. One would think being able to flip your shield and plow through it would make the game easier and for the first level or two, it does. Then you realize that the next logical step is to shoot obscene clouds of both kinds of bullets at you at the same time. Commence cognitive overload.
"I've heard the Ikaruga can squeeze between bricks in a wall without touching them."
Giga Wing is an unusual case in that it doesn't reach truly bullet hell-level until the last stage (and the TRUE last stage, of course); in fact, the first three stages look like an ordinary Capcom shooter. You also have a continually-recharging reflect barrier which not only saves your life but is key to racking up huge scores (in fact, the latter is what you're supposed to use it for). If there were such a thing as "proto-danmaku", this would be it. It does have a brutal requirement for getting the good endings, though.
Paris. You have the sheep that launch 8 homing missiles at once, the birds and owls that throw very fast feathers directly downwards, and the paper planes that launch very fast aimed attacks.
The Paris boss's final stage. You have to avoid 2 sets of radial attacks.
The Abyss boss's second, third and final stages. The second you have to avoid richocheting missiles and fast and sudden aimed shots, the third you have to avoid very fast radial attacks, and the final you have 2 sets of very dense, very big radial attacks to avoid. Harsh stuff.
StarCannon, an online game on FunOrb, easily qualifies for this trope, with generous quantities of lasers of all shapes and sizes from all bosses and most harder enemies. Just dodging the enemies themselves as they swarm onto the screen is a challenge in the later levels. A True Final Boss awaits those who complete the game on Hard.
Zanac could be considered an early example. If you fire too much, the adaptive AI will send everything and the kitchen sink after you, filling the screen with enemies, bullets, and missiles (every one with its own firing pattern). Also, the boss fights can get very hectic bullet-wise.
Vasara and its prequel Vasara 2 have a sci-fi take on jidaigeki. One interesting feature is that running into most things doesn't do Collision Damage, but you will definitely collide, which can work for you (obstruct a fleeing enemy's path and kill more in one stroke for extra points) or against you (when accidental, it usually knocks you right into a bullet you just dodged).
The BIT.TRIP series of Wiiware "rhythm" games, though each game has a separate mechanic, and they're as much about hitting the bullets as dodging them. The first has you reflecting the bullets with what is basically a pong paddle, the second had you shooting the bullets from a point in the center, and the third had you collecting all the black bullets and avoiding the white ones.
The fifth one in the series flat-out admits that it is, in fact, a bullet hell shooter, right down to the glowing hitbox in the center of your character.
Knights in the Nightmare is nominally a strategy RPG, but the enemies fire streams of bullets at your cursor to try and force you to end your turn early. It makes commanding your troops problematic, to say the least.
That's actually average. Boss fights are the ones you should be worried about, since those can knock off "time"*
it's the game's mechanic; see the game's page
very easily. Boss fights have very elaborate bullet sequences, sometimes on par with other Bullet Hell games. For example, one boss creates a swirling emblem that subsequently shatters into a rain of fragments that are nigh-impossible to avoid.
You Will Die is an indie game shooter for the Xbox 360 that consists of nothing but killing a boss over and over until you die. Every time you kill it, it adds more parts and weapons onto itself and becomes stronger. The game starts out fairly tame, but quickly reaches bullet hell levels of difficulty if you can survive long enough.
Prismatic Solid will literally bombard the player with ridiculous storms of bullets that really only be defended by using the Attack Drone to shield your ship from enemy fire.
A few of the bosses in G.Darius have attacks like this, notably the Embryon and Great Thing.
Söldner-X tends to reserve its Bullet Hell moments for boss battles. The sequel, Söldner-X 2, increases the tempo and makes the whole game like this, with Dynamic Difficulty thrown in for good measure.
A lot of games from cactus display characteristics of the genre; the straightest examples are perhaps Protoganda: Strings and its sequel. Clean Asia has gameplay pretty squarely in the genre, but is a bit of a subversion in that the enemies aren't much harder then your standard vertical-scroller bosses. Similarly with Burn The Trash and Ad Nauseam 2. Minubeat subverts this by allowing you to destroy all enemy projectiles at will.
Platine Dispotif's Gundemonium Series. Somewhat unusually for the genre, the main-series games are side-scrolling. Only spinoff Hitogata Happa is vertically-scrolling.
Sin And Punishment is a game along the lines of Space Harrier or Wild Guns, but it will occasionally throw absurd amounts of fire your way, especially on the higher difficulties. Its sequel, Sin And Punishment Star Successor, runs with it, and there are very few bosses that don't fire huge amounts of bullets your way for at least one of their attack phases. Both games have hitboxes too large (roughly the size of your rather sizable character model) to put true Danmaku levels of bullets on-screen at a time, but they can sometimes present a remarkable simulation.
The sequel XOP Black is an even better example, featuring denser bullet curtains and secret bosses, on the basis it wasn't intended for commercial release so the creators could be as brutal as they liked.
Fat Cat isn't nearly as hard as some of these examples, but it takes the cake in that many of the later bullet patterns really aren't possible to dodge. You control two characters, one small, fast, and Immune to Bullets and one large, slow, and decidedly not, and in order to keep the latter alive through the endgame, you need to rapidly circle the former around it and scrub the bullets before they hit it.
E Xceed is a doujin series that is heavily influenced by the above games.
Nanotek Warrior, a Playstation game, may qualify. While the perspective is different (the player ship is running down a cylindrical tube, which you can rotate over completely) and there are less bullets, enemies ''cover'' the entire tube/level and you'll need some impressive reaction times to dodge everything. One ad campaign for the game even stressed that having eyelids was a liability.
Sentimental Shooting features the typical bullet-hell gameplay, with one notable exception: The background is a picture of a girl, and her clothes are destroyable by your (apparently tiny) ship's guns. The real objective is not just to survive and destroy the boss, but to shoot all her clothes so you can proceed to the second stage, where the girl's underwear is destroyable. A more original way to turn a bullet hell game into a Hentai game than by just showing some h-scenes in the cutscenes, you have to give the devs that much.
Cyvern: The Dragon Weapons is another rather obscure one. Which features cyborg dragons that shoot missiles, drop bombs, and have one heck of a Breath Weapon.
Hellsinker is a very strange doujin game with plenty of unusual gimmicks and perhaps one of the most complex scoring systems to ever grace the genre.
Some of the bosses actually rip off spellcards almost directly! (The second Bonus Boss rips off a few of Flandre's. The third has 2 phases of Utsuho's Mega Flare minus the shrinking bullets (the second phase coming from below, which in turn resembles a couple of SA's bonus boss's spellcards (in the fact that the second is the first one in reverse).
Space Arcade starts out easy, but gets very bullet-hellish in its later levels.
Stella Vanity. Even in the current trial, Easy is comparable to Touhou's medium, Hard is comparable to Touhou's lunatic, Nightmare is comparable to DDP Daifukkatsu's Ura loop, and Pandemonium has you looking at something like this◊ for 70% of the stage.
Prelude to the Destined Calamity (aka the "OLD" version, released at C81) manages to have mooks that trip the software slowdown by themselves on Easy. Not Elite Mooks, Your usual cannon fodder mook. Suffice it to say, you better learn how to cancel enemy bullets fast.
Engage to Jabberwock is a hybrid of Zelda-style dungeon exploration and bullet-hell projectile fights.
The fight with Tor in Iji. He has multiple attacks that aren't too hard to dodge on their own, but at his hardest he uses several of them at once or in sequence, making full health and armour upgrades a must unless you're well-versed in this genre, or if your name is DanielRemar.
While fighting Dracula in I Wanna Be The Guy, he occasionally fires a spiraling pattern of fireballsapplesdelicious fruit. The fight against Mother Brain can get very hectic (and frustrating) as well. There is also an Unexpected Shmup Level near the end of the game, and considering what kindof game this is, it's not hard to tell how that turns out either.
Actually, to those who play shmups often, the Unexpected Shmup Level was one of the easiest rooms in the game.
While primarily an Action-RPG, Nie R often has bosses that fill up the whole screen with danmaku. When mooks later on get the same ability along with one of your companions, some fights look akin to a particularly flamboyant fireworks display. The DLC makes all the "bullets" look like No.7's head, which might either be horrific or just creepily amusing.
Many of the bosses in the Ys remakes on Nightmare difficulty. Especially Dark Fact. On a slightly lesser scale, Darm in most version of Ys II attacks with a constant rain of fireballs, combined with Teleport Spam making him even harder to hit without getting hit yourself.
Touhou has a few fighting game spinoffs, with quite a few characters fighting with danmaku as they normally would.
This causes many problems when they are ported to M.U.G.E.N, as the vast majority of 'proper' Fighting Game characters just aren't equipped to deal with such projectile-heavy gameplay.
The Ninja miniboss of Area 3 in Contra ReBirth has as one of its attacks a Bullet Hell pattern of laser shuriken.
Epic Battle Fantasy actually did bullet hell BEFORE the actual bullet hell spinoff! One of Lance's attacks in the third game is named Bullet Hell. There are indeed a lot of bullets in the animation and it hits a number of times (not that it means much, considering there's no damage cap.) The hell part becomes more applicable once you consider the attack is fire elemental.
Mischief Makers: The first and second battles with Lunar (the wolf with the machine-gun). The first battle is in a snowfield, where he fights you by shooting his weapon of choice and launching bombs, too; the second battle has Lunar on his motorcycle, launching missiles, shooting fire blasts, and also firing a giant laser whenever he gets the chance.
ThisPuella Magi Madoka Magicadoujin game is about maneuvering Sayaka's Soul Gem away from the rain of tears. It starts out fine, but after a while, there'll be so much of it that the difficulty hits this trope.
The Twin Val'kyr boss in World of Warcraft: in a Shout Out to Ikaruga you choose either white or black colour and have to catch the bullets of your colour so that they won't harm others. Mixed up with occasionally all raid having to switch to one colour to absorb a massive bomb or deal more damage to one of them. However, with advancement of gear and now level cap, people begun to just stand there and annihilate them with superior firepower.
Wartech: Senko no Ronde has this for the boss fights. Also, the normal characters can power up into B.O.S.S. mode and perform this sort of attack while powered up.
Distorted Travesty and it's sequel mixes this with Nintendo Hard with bosses throwing huge waves of bullets around. In fact the two short flying levels that more closely resemble traditional Bullet Hell are relatively easy, seeing as the rest of the game doesn't give you the luxury of bombs.
The fight with Xemnas in Kingdom Hearts 2 may count. Near the end, Sora and Riku are surrounded by umpteen of those shots he fires, and you have to button mash triangle and square to avoid damage, where the two do insane maneuvers to dodge.
Every other boss battle in Skylanders: Spyro's Adventure involved Kaos alternating between him attacking with spells that are basically full blown bullet hell patterns based around Water, Life, Undead and Fire and spawning Evil Knockoffs of three of the Skylanders of each of those elements, with the final phase of the fight having him do both at the same time. This gets cranked Up to Eleven in the final battle.
It shows up in the sequel too, though not as often.
A rare example where the player is given this ability: Warriors Orochi 2 adds newcomer Himiko, a shamanistic goddess. Her floating clay dogu can send out several dozen bullets in various flashy patterns, in addition to lasers. Her R1 special doubles the bullet count for a period of time.
If you're doing it wrong, Roarmulus Twins boss fight can play out like this.
Saint Seiya: Sanctuary Battle has the boss fight with Virgo Shaka. To say it's pure Hell is an understatement - Shaka's projectile spam is ridiculous, and chances are you will die many, many times there. Cancer Deathmask can be very annoying too with his floating skull summons, but at least Deathmask's attacks don't paralyze you and expose you to further attacks by him. Shaka's do.
Shinywuffles, naturally. I mean, just look at this.
Word is, that's level two of thirty-six.
Super Robot Wars occasionally has attacks that resemble this, such as scattering beam cannons; however, the best example is the attack some battle stations have, which involves barraging the enemy with its own weapons while summoning a horde of Mooks to do likewise. Super Robot Wars Z 2: Saisei-hen has two big examples of this, Libra and Damocles.
For a survival horror game, Demonophobia is full of bullet spamming bosses. This poses a lot of trouble considering your character moves around like a log.
Magaki, the final boss of The King of Fighters XI is the fighting game personification of Bullet Hell, as he spams projectiles from all directions (including from your behind) all at the same time.
Zandronum, a multiplayer sourceport for Doom, becomes this in certain modes and mods. Have you ever dodged a giant Cyberdemon spamming rockets in a 3-way spread toward you while having only enough hitpoint to survive only a normal level imp's clawing?
Doom itself can become this if you meet too many enemies at once. Icon of Sin on Nightmare? GG
Mega Man 8 Bit Deathmatch is a great example, specially in maps where you can easily be in everyone's sight. Add the fact that pretty much every weapon is a projectile.
Someone made a Contra and a ''Super C' mod for this game. There will be a race for the Spread Gun.
Mook Maker: May have the usual type, or more commonly bullets that fire smaller bullets.
More Dakka: The most common form of attack, trying to see if players can dodge a swarm of bullets rather than just a single one. It has the best chance of working if the bullets are tightly packed and/or fast.
Pinball Scoring: Up the backside. This is especially prevalent in games that allow you to cancel bullets (without using a Smart Bomb), as canceling bullets gives you some form of points (combo increase in DoDonPachi DaiFukkatsu Black Label, bullets turning into gems in Mushihimesama Futari).
Recursive Ammo: One of the many sources of additional bullets and changes of attack direction.
Robo Teching: Don't count on bullets continuing to move in the direction they are fired. Some types will home in, others will change or even reverse the way they're moving just to screw with you and give something else to worry about.
Scenery Porn: The curtains of coloured bullets raining down can be beautiful and hypnotic, shame they are trying to kill you.