You control a battle tank (the Rotor) which hovers in a 2D-labyrinth. Gravity pulls heavily on the Rotor, making it fall towards the ground. As any contact with walls or enemies is deadly, your main task is to avoid that. You may rotate your tank freely and accelerate via an afterburner, thus manoeuvring through the corridors.

Scattered throughout the 18 different fortresses are boxes. Shoot these open to find
Fuel: this will replenish your supply, which is drained by shooting and accelerating.
Sun crystals: Collect all to finish the mission.
Bombs. They will explode in 30 to 60 seconds, destroying your ship. You can avoid that by leaving the screen quickly, or by picking the bomb up; this earns you major credits, but your ship drops much faster due to increased weight.
Pearls. Collecting these advance the upgrade counter by one to three steps; you may activate the current upgrade at any time, which will improve your rotation speed, engine strength, weapon, shield etc. Boxes are emptied by carefully flying very, very close to them and activating a tractor field.

The game also confronts you with various enemies. All of these are immobile and fire in a straight line; the sheer mass of them makes avoiding the bullets a difficult task nevertheless. Apart from turrets, there are attractors and repulsors who'll smash you into walls, and force fields that need to be deactivated by finding and shooting a switch.