Crawlspace: 21 and Over

From publisher blurb: The crawlspace is that spot where the light of the outside world doesn't quite reach. It's separated from both the light above and the dark depths below. You can hear life going on above you while you gasp for breath in the fetid vapors rising from below. It's the place nobody thinks about until they have to go in. The core of the Crawlspace Role-Playing Game goes at least as far back as 2010 and is still evolving. This particular version was developed from Crawlspace Deluxe in order to make the TerrorHog scenario an all-in-one product. What you’re looking at now is that set of rules, with character generation, advancement, and a few other special treats and tricks thrown in.