The object of the game is to perpetuate the race by introducing ten pods in the incubators which can be found all over the ship. The alien has an energy level which slowly decreases. The only way to restore the energy levels is dropping the pods in the incubators, or else devouring the little engineers to be found on board the ship. The creatures can defend themselves spitting paralysing acid, or hiding in the air vents, etc.

The ship consists of 142 areas divided into four zones, which are joined by doors or air vents. Each zone has various levels, which are entered by lift. To enter a lift, a door or a vent, you only need to place yourself in front of it, and duck.