I'm not a big fan of the genre but I do like the sci-fi versions as in the "I am Legend" movie. So I guess I'm the opposite of Korash on this point. That said, it might be hard to bring together fantasy backgrounds and sci-fi backgrounds but as far as the world and mapping goes I think it would be cool. Also, such maps could work for a big variety of games. (eg. any post apocalyptic world)