Something is opening Holes, corridors into other dimensions, which are destroying the Earth's ecological balance. These passages are filled with hostile aliens and mechanical life-forms. Your objective as a Trained Holebusting Operative is to get to the core and destroy it. This game is a cross between an RPG and a miniatures game. Players command a squad of 12 humans as they battle their way into a randomly generated maze of corridors. The game uses a d100 for all combat resolution and lets players choose a few modifiers if they want to expand the No-Frills Combat System.