SNK‘s Twinkle Star Sprites was released for the Neo Geo in 1996 and is an interesting mix of vertically-scrolling shoot ’em up and head-to-head puzzle game. Yes, I know that sounds weird, and this game IS weird, but weird in all the right ways…
The idea is: you compete against another player (or the computer AI if you don’t have any friends) in a split-screen environment. Enemies come down the screen in waves and shooting them in chains (combos) sends fireballs (and other special attacks) towards your opponent, and vice versa. Combo attacks can also be reflected back a number of times, creating indestructable enemies and even summoning a Boss Battle. Whoever loses all their “life points” first loses the game. So Twinkle Star Sprites is less “bullet hell” and more “opponent hell”.
Graphically, Twinkle Star Sprites is full-on, Japanese, mega-cute Manga, and the humorous and wildly-colourful visual style suits the manic gameplay perfectly.
More: Twinkle Star Sprites on Wikipedia