The best laid plans of dice and lan often go astray.
I would use Marvel Super Heroes (they have old west characters as well as aliens). Either that, or play around with Mutants & Masterminds. Ciao!
This looks like it would be a perfect use for Mutants and Masterminds, or even one of the more "serious" flavors of Risus.And yes, I thought the same thing when I saw it. :D
Deadlands. This so screams to use Deadlands.
Deadlands (Savage Worlds system right?) would be a cool one to use I think, you just need to worry about the Aliens at that part...
Yeah, I gotta say Deadlands.