Cell War puts you in control of a tiny spaceship which travels through the microworld. Viruses of all shapes and sizes threaten to destroy your ship, but you are prepared for them. There are 9 stages where you must fight off the invading baddies, with three skill levels from which to choose. As you increase the difficulty, you'll encounter more enemies on-screen at any given time, splitting your focus and challenging you to stay alive. Enemies shoot little yellow balls at you that must be avoided, as they don't seem to be able to be destroyed by your weapons. Destroying enemies leaves behind objects which must be collected if a cure is to be found to eradicate the nasty viruses that you are fighting. Fly close enough to the objects and they will be pulled into your ship. If you're lucky enough to make it through the throngs of viruses, you'll encounter bosses at the middle and end of the levels. These are obviously bigger and more difficult to kill than the smaller viruses, adding another great challenge to this fun game.