Ikaruga Cheats

To get an infinite amount of continues, register eight hours of total gameplay. Keep in mind that as you go up in hours (from one, to two, to three and so on), you'll unlock more and more continues until you hit eight hours, which will unlock infinite continues.

Ikaruga Unlockable: Prototype Mode

To unlock a new mode in the game called Prototype Mode, beat the game once through in its entirety.