You have been sent into a building infested with robots, and must do your best to clear it out.
Each rooms has a number of walls through the middle, which restrict your movement.
There will be a number of bad guys in the room – on early screens they may be immobile and not shoot at you, but after a few levels they become capable of shooting in multiple directions.
You can shoot at them in 8 directions, but can’t shoot diagonally while moving.
There are gaps at the side of each room, through which you exit, before or after clearing the room.