Sega Asteroids is an arcade space shooter released in 1979. This game is a licensed Japan release of Atari Asteroids; this is not to be confused with Taito Asteroids (which was also a Japan release of the original game).
The objective of this game is the same as Atari Asteroids. You control a spaceship destroying asteroids and UFOs. You can move freely anywhere on screen and you can sent your ship in hyperspace, causing the ship to disappear and reappear to a random location.