I've never played anything like that myself, but its a damn fine idea. The
Red Rain trilogy are actually some of my favourite Batman comics (an unpopular stance, I know).
I think it would be easy enough to have a Batman very reminiscent of the Golden Age Sandman, or a bit more Doc Savage-like, and that would fit in nicely with a 1920's Cthulhu setting.
Also, there is a bit in the movie
Batman Begins, where he is swooping out of the darkness, picking off gangsters at the docks one by one and terrifying them. Its more like
Alien than Adam West. I don't see why Bats couldn't make the jump to the horror genre.
