Ikaruga(斑鳩, lit. Japanese grosbeak) is a vertical manic shoot 'em up video game developed and published by Treasure. It was originally released in Japanese arcades in 2001 on the Sega NAOMI platform, and is the spiritual sequel to Radiant Silvergun. The gameplay consists primarily of a polarity mechanic. All enemies and bullets in the game are either black or white, and the player may switch between these polarities at will. Bullets which are the same color as the player are absorbed while the other will kill the player. The game features both single-player and cooperative modes.