The player controls the trans-dimensional spaceship, and must battle waves of enemies through various environments.

During the game, many enemy craft leave behind icons or 'pick ups' when destroyed. Collecting one of these will shift the section cursor along the weapon bar at the bottom of the screen.

The player can then select the weapon highlighted(press B button) if they want it . The cursor then resets.

In general, the more useful 'power ups' are towards the right hand side of the bar, so the player may decide to stock up on pickups until the better item is available.

This innovation allowed for deeper tactics on the part of the player and for greater freedom of weapon choice rather than relying on the pre-determined power ups common in other games in the genre.