What is "ikaruga"

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.

Ikaruga was developed with a core team of only three people for over two years. All the characters and enemies in the game were named after various bird species. The game was well received by critics and is considered one of the best shoot 'em up games of all time. Ikaruga was ported to consoles first in Japan on the Dreamcast in 2002, and then worldwide on the GameCube in 2003. An enhanced port was released for the Xbox 360 in 2008 and later ported to Microsoft Windows in 2014.

Many of the ships in the game are named after bird species. Ikaruga (斑鳩), the titular ship which is controlled by player one, is named for the Japanese grosbeak. The name of player two's ship, Ginkei (銀鶏), refers to the Lady Amherst's pheasant.