In the game, the player controls a small blue spacecraft. The game starts in a fictional solar system with several planets to explore. If the player moves his ship into a planet, he will be taken to a side-view landscape. Unlike many other shooting games, gravity plays a fair part in Gravitar: the ship will be pulled slowly to the deadly star in the overworld, and downward in the side-view levels.
The player has five buttons: two to rotate the ship left or right, one to shoot, one to activate the thruster, and one for both a tractor beam and force field.
In the side-view levels, the player has to destroy red bunkers that shoot constantly, and can also use the tractor beam to pick up blue fuel tanks. Once all of the bunkers are destroyed, the planet will blow up, and the player will earn a bonus. Once all planets are destroyed, the player will move onto another solar system.
The player will lose a life if he crashes into the terrain or gets hit by an enemy's shot, and the game will end immediately if fuel runs out.
On the 24th of March 2010, Gravitar was added onto the Xbox 360 and Games for Windows LIVE service, Game Room at a price point of 240 MS Points for a one-platform purchase, or 360 MS Points for a purchase on both platforms. For 40 MS Points, a user could play a one-off game. In July 2010, the Atari 2600 version of Gravitar was added to Game Room as well.
Source: Wikipedia, "Gravitar", available under the CC-BY-SA License.