It's neat to see the way that they are creating this mode, but I'm not really sure why people seem to think a "supernatural western" is all that big a deal. I mean it's been done quite a few times before as far as I can tell. The Western being one of those generes that has taken a ridiculous crossover beating through the years. I mean if you look you'll find that movies like "Billy The Kid meets Dracula" actually exist.
This is to say nothing of the fact that there was an entire RPG setting called "Deadlands" which was fairly popular for a while. It spawned probably a dozen supplements, a bunch of fiction, and two spin offs taking the setting from the West, to post Apocolypse (after the 20th century), to a colony out in space. It managed to see print under two engine simultaneously... D20 and it's own game specific engine.
While by no means brand new, this isn't ancient either, and as far as RPGs go that aren't run by one of the big three (D&D's current liscence holders, White Wolf, or Palladium) that's pretty bloody impressive as far as PnP RPGs go.
Deadlands featured everything from Zombies to Cthulhu like entities, and all kinds of creepy crawlies, zombies were however a mainstay. The idea of having the four horseman of the Apcolypse running around also seems to be directly from that setting as well.
Conceptually in Deadlands you had the idea that places were slinking into evil and fear due to some cosmic disturbance, in certain areas things go so bad that reality started to fall apart and monsters would start appearing and doing monsterous things. The PCs would ultimatly wind up having to head in and kick monster butt, but simply winning wasn't enough, they had to inspire the people to transform the area back (at least for a while) which involved a game mechanics where part of the adventure (as the conclusion) was typically to spin overblown tall talls (even more overblown than the actual adventure) of what the PCs did in order to win, to rally the people so their will would stave off the darkness.
It was REALLY wonky...
At any rate, the point here is that I just don't see how "it's a western with zombies" gets any real points for being new and original at this point. Heck, even Deadlands was inspired by a lot of the horrible schlock western crossovers that have appeared over the years, and wasn't getting many people giving it kudos for being paticularly original so much as bizzare and "OMG, someone actually made this playable".
I like this add on for RDR, but really I think comments about it should be a little better tempered to account for what has come before. Nerd education so to speak.
I wonder if in a few years I could rip off something like Fu Manchu wholesale and have people tell me it was the most original thing ever.