Before I start, I just wanted to say: I absolutely loved the concept of Vermis, it's a cool read (even if the second book isn't as good).
That got me thinking: What about an RPG where the objective is for the PCs to die heroically?
Off the top of my head, the concept is like - the entire world is rotting, and everyone who dies goes to Hell to suffer forever. The only way out is to die heroically so you go to Heaven, to escape Hell's grasp.
The PCs are a desperate band of heroes who have set out to cheat Hell, by trying to put themselves into situations where they can die in genuinely heroic ways, saving their souls (I'm somewhat thinking of Fate of the Norns: Ragnarok.)

Of course, just getting stabbed by goblins or dying in a fight isn't enough, you need to do something REALLY heroic and sacrifical or you're damned forever. So you can't just pick a fight, you need to find somewhere you can make an 'unforced' sacrifice.
I think OSR can work for this - I feel other RPGs don't really suit the morbid black comedy of this idea.