Fleets of alien vessels are quickly approaching the Space Fortress! They are overwhelming and there is no chance of victory. However, they can be held off as long as possible. The space fortress weapons will destroy as many as possible.Space Fortress is a static space shooter. The player sits at the controls of the Space Fortress and can alternate between management of targeting (weapons), power allocation, damage control, powerup retrieval and powerup usage. At all times, the radar image will be represented on the screen showing any approching enemy ships. By taking control of the weapons, the player can blast the enemies using several different types of weapons. Each consumes energy, and enemy hits deplete the space fortress' shield. Defeated enemies leave power-ups which must be retrieved with probes and brought back to the space fortress for use. The game ends when the space fortress is defeated: Either by having it's reactor go critical, or by losing all of it's oxygen and life support.