You'll have to work through seven houses, each of which has the typical rooms. You control a seemingly-dismembered hand, which must deal with the hordes as they come towards it, into the screen. They can be shot, thumped, or squashed depending on their type. To clear a room you must kill a certain number of creatures in each of the vertically-divided 'lanes' of the room - this causes squares on the ground to change colour.