Get Fallout 3 on pc. Download the GECK (Garden of eden creation Kit) from Bethesda. Learn how to use the GECK, and make that which you seek. Yes, it would be a lot of work. Basically a total replacement of the quests, textures, maps, and NPCs, but it could be done.
It'd take someone a lot more skilled with the GECK than me, however.
I can do some things, just not an entire re-write. Mostly things like locations, quests, and NPCs. No meshes, textures, or animations.
The good news is, there are a *LOT* of Mods already made that you could either incorporate directly or borrow elements from. All you'd need to do is ask the mod creator if you could use it, and not be doing this for profit or commercial use. And finding directions on how to do the modding is pretty easy, too.
I say Fallout 3 and not Fallout: New Vegas because IMO Fallout 3 is much, much better. Mods turned Fallout 3 from a great game to a truly outstanding game. OTOH, Mods made Vegas basically playable. I also hate Steam and won't advocate anyone using (paying for) anything that requires Steam.
If anyone decides to mod Fallout, whether for a T2k game or just to have more fun with Fallout, go to the Fallout 3 Nexus. All kinds of great files. I especially recommend Fallout Wanderer's Edition, 19th & 20th Century Weapons, and Mart's Mutant Mod. *I didn't write those mods, nor do I know the authors or have any kind of special interest in them other than the fact that theyre some of my personal favorites.*