I've played (or at least read about) quite a few Western-themed console games, I'll give you the skinny on what I know so far:
RDR2 hasn't been officially announced yet as far as I know. It was Rockstar's PS3 tech demo of an "untitled Western game" that got everybody all abuzz about it back before that system was even released. But given the fact that RDR sold fairly well, I wouldn't be surprised if Rockstar eventually made a full-fledged sequel. Here's hoping, as it's my favorite Western-themed video game by far.
As far similar titles are concerned, there's of course the aforementioned "Gun" (another terrific game), as well as a first-person shooter for Xbox entitled "Dead Man's Hand" that is mediocre at best. DMH has a decent overall look and feel, but the frame-rate is pretty choppy, the kiss of death for any FPS. ("Halo 2" it's not.) "Darkwatch" and "Oddworld: Stranger's Odyssee" both have Western slants, but really aren't true Western games.
Let's see, what else? "Samurai Western" for PS2 puts you in the role of a samurai in the Old West (big surprise there!). It's fun for awhile, but the nonstop hacking and slashing gets repetitive after awhile. There's another FPS for PS1 called "Jesse James: Gunfighter" (if I remember correctly) which is pretty awful, I think it may be a European game, so it may not be available in the States. There's also "Rizing Zan: Samurai Gunfighter" for PS1, which I haven't actually played and have only heard about.
If you really want to go old-school, who can forget the classics "Gunsmoke" and "Sunset Riders"? The SNES version of Sunset Riders is still a blast, easy to find on emu as well! And what was the name of that Atari 2600 game? "Outlaw" was it? That game rocked! "Mad Dog McCree" too!
Of course, the deeper you delve, the more you lose the whole "spaghetti" element, but a lot of these Western videogames are still fun to play whether the Italian influence is there or not.