Re: Genre-crossover nightmares
I actually played that. A friend of mine had a D&D adventure based on The Keep (film) which was about Nazis inadvertently awakening an ancient evil. So there was the usual dimensional rift thing and the D&D party found themselves in combat with the SS, a few Panzers, and a horrifically powerful vampire warlock. I have all kinds of bad memories of the session, first because I don't like machine guns in my fantasy, second because the module was really frickin' hard, and third because I got into several arguments with the GM that in hindsight were the result of a ruleset that really couldn't handle modern weapons at all.