Owl Hoot Trail adds classic fantasy RPG races and character ty to a Western setting.
Werewolf: The Wild West covers the setting for the classic World Of Darkness. (Victorian Age Vampire covers the same era, of course, though the Victorian Age Companion with its sections on ghosts and other monsters is probably more useful to a general game.)
Dogs in the Vineyard can be tuned up for more supernatural elements. Demons can actually be no-shit demons, or they can just be another name for people being shitty people. Likewise, the Dogs can actually use powers from God, or it can all just be rituals and mummery.
Its brutal, episodic, and has some really nifty features; my personal favourites are character creation being resolved as a card based minigame and the simple system for Infernal Pacts. In honesty I think its still in alpha development, but it's real simple and works elegantly once you wrap your head around it.