The setting is a large space city, over-run by hordes of mutant gremlins. You have been delegated to clean up by destroying the Invaders and their spawn. To do this your force of eight troopers have to carefully explore the city and attack the enemy with weapons left lying around. There are many features to the game and you have to puzzle out the best tactics and weapons to use. Complications are that various emergencies arise in your support systems, and these must be quickly dealt with.
You can control any of your troopers individually while he or she is alive, and score points for killing gremlins. There is a fixed time limit and any of nine skill levels can be selected.
The display consists of an impressive scrolling plan of the city with you at the centre. Colour and sound are well used to enhance the battles and special effects.
A game that needs time to play and careful thought for a high score. It makes a pleasant change and offers the chance to exercise your brain as well as fingers.