The Northstar space station has been overrun by aliens, with all reports suggesting that the crew didn't survive. It's your job to progress through its floors, wipe out the aliens and restore order.

What this entails is essentially a case of walking from left to right taking out everything you see. You are armed with a lance, which you can use from some distance, although you can only attack in one direction at a time, although aliens can come at you from all around, many of them using some wicked patterns. There are ledges to be climbed, the lance can be used to hoist your way up.

Enemies often give off bubbles (for points) or stars (collect for an extra life). You are limited in the amount of oxygen you have to complete a level, and you have 4 lives, one of which is lost on contact.