Scientists experimenting with radiation have accidentally mutated all underground life forms which are now intent on taking over the world, so you, of course, must save the planet from certain destruction. (Sounds familiar.)
This is achieved by placing eight pieces of lead around the radioactive source. The lead can be picked up at points around the maze and only one piece can be carried at a time. A lot of going back and forth in your little grey tank is required with all this movement depleting fuel.
Fuel tanks are scattered around then map which must be shot at for extra fuel. Stores of ammunition must also be found and shot at for a top-up. Routes are blocked by lasers which can be turned off by touching a series of switches in the right order. Passcards can also be picked up and open locked doors. In addition to locked doors, there are also plenty of mutants standing in you way. These mutants get stronger as you progress through each level and they finally have the power to shoot back at you.
Each of the four levels has a map of thirty screens which should keep you busy for quite a while, considering the speed of your tank. The graphics look dated and the tank moves too slowly to keep you interested in the game. Sound effects are limited to a few bangs and buzzes with no title tune. There's just not enough gameplay in Hideous to warrant much interest.