Siroi Danmakukun is a distillation of what excites (or frightens, or terrorizes) many modern shmup players: insane patterns of bullets. The goal of the game is simply to survive as long as is humanly possible. Minimalistic graphics (you are a ball, as are the bullets), no sound, Japanese/English menus. You and the bullets.
http://repo.openpandora.org/?page=detail&app=siroi-sdmkun-23247