The marine is outfitted with the snazzy Exolon suit, a powerful exoskeleton equipped with a hand blaster and backpack grenade launcher, and it is these that will facilitate your progress. The screens, or ‘zones’, are occupied by a mixture of targets. Some feature aliens themselves who swarm from right to left across the screen indefinitely. These can be taken out easily with your hand blaster but there are also ground-based guns and missile-launchers which can only be taken out by grenades, and it’s the same for the non-hostile but still inconvenient obstacles which appear to consist of hardware such as satellite dishes as well as strange alien structures.