As much as I love the Deadlands setting and its alternate-history stylings, I have definitely come to terms with the fact that it's really codified a lot of what constitutes Wild or 'Weird' Western gaming nowadays. In the same way that fantasy RPGs are expected to have elves, bags of holding and giant abandoned tunnel complexes under most mountains, the 'Weird West' tends to contain a fistful of steampunk technology, some real-world figures that are actually demons or Draculas and a few Native American ancestor spirits, all topped off with zombies, zombies and more zombies. A lot of genre works or roleplaying games replicating genre works can get bogged down in this inspirational marsh: potential players want to have a certain amount of familiarity in their settings, a sort of 'buy-in' that allows them to imagine the world more clearly than a written description.
If I ever run a Western game of any stripe in the future, I want the buy-in to be the Western genre itself. There is so much unexplored gaming territory in the straight or slightly twisted Western just waiting to be mined that it's almost criminal. Action and suspense fans can have gunfights on top of moving trains or high-noon showdowns, planners have bank robberies and jailbreaks and social gamers have poker games and contests of intimidation. If I ever wanted to add Weird elements to the game, it would be more as an accent to the ongoing action rather than the be-all and end-all of the campaign. It would still be a recognizably Western game, just with a couple of interesting tweaks to vary the formula, not transforming the game into a fantasy or horror campaign with Western trappings. Of course, this is under the assumption that the only way to add Weird elements to a Western game is by including the supernatural or other types of mythical monsters. There are plenty of ways to make your Western weird without delving into the codified lists of fantasy creatures in spurs and Stetsons.
I think I'm going to take a couple of entries to talk about the different ways that a campaign can still remain a Western game at heart, even while adding strange or extraordinary elements to the mix.