Warning Forever

Warning Forever is a Bullet Hell game developed by Japanese freeware programmer Hikoza T. Ohkubo available for download here. In the game, you play as the pilot of a starfighter tasked with defeating an endless series of enemy bosses. The game is notable in that the enemies actively adapt to your tactics; if you've been focusing on destroying one particular segment, expect that segment to be reinforced. Likewise, if a certain weapon kills you, expect more of that weapon in the next form.

It also inspired the real-time tactical game Battleships Forever and the Xbox Live Indie Games title Infinity Danger.

This game provides examples of:

 * Adaptive Ability
 * Beam Spam
 * Boss Game
 * Boss Subtitles - Of course!
 * Bullet Hell
 * Cognizant Limbs - The different sections of the bosses are all individually destructible.
 * Collision Damage: Oh yes. Gets real bad when the boss evolves into something HUGE.
 * Death in All Directions - Including:
 * Beam Spam - Laser
 * Macross Missile Massacre - Pod
 * More Dakka - Vulcan and Needle
 * Ramming Always Works: "Force". This isn't exactly a weapon, but allows the boss to propel towards your character, and if the boss is too large you may not be able to avoid getting killed.
 * Shotguns Are Just Better - Smash
 * Spam Attack - Yes, melee. The enemy's Cognizant Limbs may track your movement and try to smash your ship.
 * Spread Shot - Cannon
 * Deflector Shields: in higher evolutions the boss can surround segments in a glowing field that makes the segment indestructible (although this may also may be a kind of power armor rather than a shield).
 * Dynamic Difficulty
 * Endless Game: In theory, anyway. Eventually the enemy ship will get so big you'll die multiple times just from having it come on screen, let alone fire, which is basically game over.
 * Frickin Laser Beams
 * Guide Dang It: How to get the boss to evolve into the "ISE-ONE" form. You have to kill the top/bottom two "corners" before killing off the core of a form WITHOUT hitting the bottom/top two, so that the top/bottom will evolve into an "armor" form. Then you have to do the same with the other side, again NOT hitting the (already evolved) opposite side.
 * If done correctly, both top and bottom sides will have the "armor" form, which will eventually make the boss evolve into the ISE-ONE.
 * Names to Run Away From Really Fast - The early ships have simple names like "The Wider" or "The Attacker", but as it evolves, you end up with "The Berserker", "The Armageddon", or the "Giga-Beamed Hammerhead Hell"
 * Painfully Slow Projectile - But as the game goes on, there's an awful lot of 'em.
 * Shoot Em Up
 * Spread Shot: Bosses have a regular variety (Cannon), while your ship has an aim-able Spray Burst.
 * Timed Mission - One mode of gameplay gives you a timer to beat. If you destroy the boss fast enough, you can gain time for the next level.
 * Up to Eleven- Just how outrageous can the ships get? No, more than that.
 * Video Game Lives - Another mode of gameplay gives you three lives, with the opportunity to gain more as you destroy parts.