The player's ship is protected by a shield which decreases when incurring damage from enemies, weapons (including explosions from the player's weapons), and collisions. If the shield is fully depleted and the ship takes any additional damage, the player loses one life and all rescued hostages, and the ship explodes, leaving most of its power-ups nearby. The player continues back at the start of the level with only basic armaments - to resume where he/she left off, the player must return to the site where the previous ship was destroyed to reclaim his/her power-ups. If a player loses all lives, the game will end. Shield, energy, and ammunition suppliers are dispersed among the levels to help players increase their resources, while life points are awarded at certain point levels and by picking up special hidden power-ups in the level.