Enemies swirl at the far end of the playing field, then enter it and move toward the player. When all enemies in a level are destroyed or reach the player's end of the playing field, the player "warps" to the next level by traveling down the field. As the player warps to the next level, he or she must avoid or shoot away any spikes. The player loses a ship when an enemy comes into contact with the ship, shoots it or otherwise destroys it, or if the ship hits a spike while warping. The player earns new ships at certain point thresholds, and may hold up to six ships at once. The game ends when enemies destroy all of the player's ships.