Ikaruga Easter Eggs and Unlockables (GameCube)

Ikaruga is a vertically scrolling shooter video game developed by Treasure Co. Ltd. It was released in the arcades in 2001 on Sega's NAOMI system and subsequently ported to Dreamcast in Japan and then worldwide to the Nintendo GameCube. It is a spiritual sequel to Radiant Silvergun and the introduction says it is "Project RS2" (usually interpreted as "Project Radiant Silvergun 2").

The gameplay consists of shooting enemies who come in one of two polarities: either black (red) or white (blue). The player's ship can be either polarity and can be switched at will. This yin-yang gameplay mechanic was previously explored in another Treasure game for the Sega Saturn and PlayStation called Silhouette Mirage.



Unlockables

Unlock stages for Practice and Conquest mode
To unlock a stage for Practice mode, it must first be reached without continuing. The stage is only unlocked for the difficulty level it was played on (ie: reaching stage 3 on Easy will not unlock the Normal or Hard versions). Conquest mode is unlocked the same way, except it doesn't matter what difficulty level is used.

Unlocking Galleries and Game Mode Option
Gallery 1 - Play the game for 5 hours or complete the Trial Mode without continuing

Gallery 2 - Play the game for 10 hours or clear the game on any difficulty setting.

Game Mode Option - Play the game for 20 hours or beat the game on Normal without continuing.

Sound Test - Play the game for 15 hours or beat the game on Easy without continuing.

Easter Eggs

Bullet Eater
In order to receive the "Dot Eater!" ranking upon completing a level, do not fire the Ikaruga even once. This means that you can't kill normal enemies or the boss of the stage, but rather you will have to dodge/absorb enemy fire in order to complete the level. This ranking does nothing but add extra challenge to the game.

Here's a video showing gameplay footage from the title's first level: