Man, I wish I had written this thing. Not because I am a nihilist, but because it is just so damn good. I don't even know how you could use it, except as a one-shot....unless you played through Black Sun Deathcrawl and then moved back in time to give your PCs a chance to avoid that bleak future.
Or maybe as a trip to another plane of existence.
Or maybe if you have a TPK, and you really do want to let your PCs wake up in hell. If you go with this option, make new Black Sun Deathcrawl characters, and then shuffle things up so that each player is playing someone else's PC.
This is both a setting and an adventure. The adventure is not set up to allow you to "win". It is what it is. If this isn't being run as a one-shot, you'll have to provide your own win conditions.