Masters of the Universe + Shadowrun. Basically all of your PCs are (4e) Magician Adepts, get to split their Magic rating accordingly. Eternia is a massive city-planet... and you are not the Masters of the Universe.
You can do a lot of crazy stuff with SR4.
You can take basically any WW/OP game or game line and cross it with Street Fighter: the Storytelling Game. This actually works really really well with the "mortal" splats for a different take on urban fantasy. Or Mage, for an even more esoteric game.