Allow me to give a personal ranking of the Fallout games: 2 > New Vegas > 1 > 3. I hear there are others but they didn't make the cut. While Bethesda and especially Obsidian did a great job in keeping the series alive and translating the older games' feel into 3D, there's no denying that those earlier isometric titles have a bleakness and depravity to them that cuts deep, a cynical humour about the world and human nature that leaves a real mark (and the series' co-creator has recently been dropping some bombs about Fallout's origins). Bethesda's style has its own advocates, of course, but Fallout's now such big business that it doesn't feel it'll ever go back to the tone of its earliest entries.
Luckily we have mods. And while all eyes have been on the impressive-looking Fallout: London, another modding team has been putting together a project that looks just as ambitious, detailed, and grim in all the right ways. Fallout Nuevo México welcomes players to the state known as the Land of Enchantment in 2166, five years after the events of the original Fallout. The mod runs on the Fallout: New Vegas engine and zeroes-in on parts of the series like choice and more traditional PnP-inspired RPG elements (this is, after all, a post-nuclear role-playing game). It's also fully voice acted, with its own original soundtrack, and the above video shows off around 18 minutes of this thing looking worryingly like the mod of my irradiated dreams.
A particular ghost in the machine here seems to be Van Buren, the codename for Interplay's own cancelled take on Fallout 3, parts of which have since leaked out to the public. Especially notable is Nuevo México's decision to allow the player to choose between two characters at the start, one of whom is a prisoner with no memory of how they got locked up: which was pretty much the starting point for Van Buren.
Nuevo México is taking great care to ensure the American state doesn't just feel like an area of Mexico, and features voice acting reflecting this: "we'll have more Chicano speaking characters in New Mexico, while we have authentic Mexican accents in México, this is to separate each one as their own as opposed to having New Mexico feel just like México."
The mod was originally announced around two years ago (check out the immaculate vibes of this teaser from the time) and still doesn't have a release date, though the team behind it says there are two more deep-dive videos coming, which suggests it's cooking along nicely. Bethesda's focus is elsewhere for now (though Fallout 76 is also leaning into New Vegas with its latest expansion), so the likes of Nuevo México are probably gonna be the best option for getting our radioactive kicks for a while.