Orbital Defense

Orbital Defense is an Asteroids variant. The player controls a spaceship and must protect Earth's satellite network from subsequent alien attack waves. In order to progress to the next wave, all the alien ships on the map must be destroyed. The spaceship can fly in any direction and has, by default, the same blaster weapon throughout the entire game, accompanied sometimes by missiles. Power-ups, dropped randomly by destroyed enemy ships, can be used to upgrade the blaster and missile launcher or gain temporary access to other weapons. They can also bestow temporary invulnerability.

Since the alien ships can shoot back and even crash into the player's ship, it is imperative to watch over the integrity of the hull armor. Once depleted, the spaceship is destroyed. The player loses the game either when all four satellites are destroyed or there is no spaceship left to control. However, one satellite can be recovered every time an alien wave is defeated.