The basic gameplay of Spacewar involves two armed spaceships attempting to shoot one another whilst maneuvering in the gravity well of a planet. Each player controls a ship, and must attempt to simultaneously shoot at the other ship and avoid colliding with the planet. In most versions, the ships' missiles are also affected by gravity. Some variants of Spacewar add the idea of a limited fuel or energy resource for each ship, which is expended by thrusting or firing and regenerates slowly over time. Many also add a shield, which can be erected for a short time at the cost of energy, or a hyperspace warp which transports the ship to a random place on the screen.
Some of the best-known Spacewar derivatives are the Star Control series of games, created by Toys for Bob. Originally released for MS-DOS and the 3DO console, these expanded on the Spacewar concept by offering a large number of ship types, each with its own attack and special ability. Each of the three Star Control games also added a strategic or adventure game based around the Spacewar game.