Looks like COD4: Modern Warfare still has a few tricks up it’s sleeve thanks to a new Star Wars total conversion mod by Black Monkeys called Galactic Warfare. The gameplay itself feels completely the same with only the cosmetic elements really changing. Lasers instead of bullets, electrical blasts instead of chemical explosions, etc. Not that this is a bad thing in any way. Watching an x-wing lay down some sweet destruction is quite epic actually.
The only real problem I have with it at this point is the limited number of maps, weapons, perks, and servers running it. However, the single map the beta contains is very well made, and more maps are in the works. With enough content this could become a very popular mod indeed. Specially if Infinity Ward never adds mod support to Modern Warfare 2.