Summary: The game starts off looking like the classic Space Invaders, but as you play through the game, it evolves. Unlock new stages, new power ups, and new features. In addition to Normal Mode, Challenge Mode pits you against 99 randomly-created stages. And Music Mode generates custom stages based on music stored on your console. The Invaders are back, and they're watching you. The more you play, the more the game evolves!