The player controls a small flying sheep and has the task of defending the planet by shooting down aliens, and preventing them from charging up their "planet buster" gun.

Like Llamasoft's 1984 release Ancipital, the game makes use of multiple gravitational fields - there is a landscape across the bottom of the screen as per a normal shoot 'em up, but also an inverted one across the top. If the player is in the centre of the screen, the projectiles the sheep fires fly straight. Getting closer to the land at the top or the bottom of the screen will cause the projectiles to curve up or down respectively, allowing the shooting of aliens close to the surface. Proximity to the upper and lower surfaces also affects movement speed which becomes slower when near either surface.

The player can land the sheep on areas of grass on either the top or bottom of the screen, in order to reduce its hunger. A stomach meter shows the player's current state of hunger - overfeeding or allowing the sheep to starve will result in the loss of a life. Feeding also replenishes the sheep's shields.

Destroying all of the aliens advances the player to the next level, which has different topography and is slightly more difficult. There are 48 levels in total