Ikaruga is a vertical shoot-em-up game ported from the Naomi Arcade version, and it's often considered a sequel to Radiant Silvergun on the Sega Saturn.
The gameplay revolves around a two-colors system, where the player must switch between the black and white sides of their ship during gameplay. The black side is immune to black enemy bullets, which can be a bonus, while it dies on impact with white enemy bullets. Similarly, your own black bullets damage white enemies twice as much as white bullets, while vice-versa applies for the white side.
This unique system, combined with specific enemy patterns and a combo system, makes Ikaruga an original shoot-em-up with a dose of strategy. The game requires a balance between protecting yourself well and killing enemies fast.
Ikaruga was released for the Gamecube on 15th April 2003.