The game begins by asking the player(s) to choose a difficulty level. The higher difficulties make the enemies stronger and the players weaker and also start the players in a later set of levels (called "galaxies") and with some powerups. The easiest difficulty starts the player(s) in the first level with no bonuses. The player controls a tank with constantly draining fuel, and must navigate through multiple levels (14 stations in the arcade version) from bottom to top, encountering obstacles and enemies. Along the way, the player may find powerups including tank fuel, stars (currency), shields, and two types of sub-weapons: smart shots (homing missiles) and bombs (powerful rockets). Each level has a key that will open a door at the top of the level, which will either take the player to the next level or to a special hub with multiple powerups that must be escaped in 10 seconds or less (15 for the NES version, though the timer stays stuck at 10 for five seconds before counting). If the player is unable to escape, the tank will lose half its fuel. After escaping the hub, the player(s) then proceeds to the next station.