That's actually a pretty sweet idea! Imagine Big Daddy's freeing the slaves of Paradise Falls! Or, Slicers using the Fat-Man on each other xDarc1991 said:fallout 3 and bioshock, rapture wont know what happen on the surface would they? =)
OT: Now that Disney and Marvel are together, I would like to see Kingdom Hearts 3 go to New York and such places as The Baxter Building or, Stark Tower. I would love to see Sora and The Avengers fighting in Latveria or, watch Goofy shit himself as Galactus descends on Twilight Town xD
Another good idea would be to mix Harry Potter into the Marvel-verse. Whose to say those witches and wizards aren't just a primordial form of Mutant? I mean, there are already so many similarities between HP and X-men xD
As a final thought: Why not mix Call of Cthulhu with Silent Hill? Silent Hill [the original idea of a town being a malevolent super-organism anyway] is a very Lovecraftian idea after all.