Just for anyone who hasn't seen it, the concept for this timeline came from a question asking "What if the Vault Dweller never defeated the Master". My response was below:
*Raspy Voice On*
With the fall of the vault dweller, there is noone to stop the rise of the mutant force. The Brotherhood, paralysed by indecision, is eventually besieged by the Mutant horde. Unable to leave their shelter without facing a rain of bullets, plasma and rockets eventually die of starvation.
The towns of Adytum, Hub, Junktown, Shady Sands, Redding, Reno, Modoc, Klamath and Den all fall to the mutant horde. The Ghost farm, able to greater trade on superstition with the lower inteligence of the Supermutants survives. The residents of vault city retreat into their vault for the meantime. With the followers of the apocalypse exterminated, and no new rome in the region, Caesar is never born.
As the Enclave become active in the californian region, it comes with a panic. The mutant horde is well armed, well equipped, and great in number - the plan has an air of drastic to it. Although Curling develops a theoretical version of the Forced Evolution Virus that could cleanse the wasteland, with no immediate access to the virus getting a sample becomes a priority. A full frontal assult on Mariposa is considered, but rejected for being too risky. The Enclave, in its desperation resorts to the tools that brought the world to its knees last time (Either using BOMB-001 from VB, another stockpile or building their own). Although Mariposa is not on the target list, the other super-mutant strongholds are. The greatly reduced mutant force, surprised from the attack from an enemy they had not yet seen is no longer able to offer the same resistance. Mariposa falls, Curling finishes his FEV work, and it is released into the atmosphere. Other than those who remain, or have rentered the vaults, the human, supermutant and ghoul population of the continential USA has been exterminated.
The calculator, detecting that the surface is okay begins its reconstruction of the old world. Using long dormant control subroutines, the Enclave takes control of its forces, and uses its resources to rebuild its version of America.
James still enteres vault 101 to protect his child. With no brotherhood to assist in Project Purity or to mitigate the mutant threat, his work is not developed enough to receive that flash of inspiration to seek a GECK. Although the memory of his abandonded work still pains him, and he continues secret research into water purification, James remains in the vault watching his child and Amata grow into advlthood, and they lived happily ever after, until the Enclave came.
Seeking a place for rest and relaxation, an encalve scouting party eventually reaches Las Vegas. Surprised to see a securitron army rebuilding the city, they eventually make contact with one of old America's favourite sons. Although there is some disquiet on his eligibility to claim humanity initially, these are mostly overcome and he eventually rises to become President of the newly reconstituted United states. With his economic and political resources, not to mention his intelligence, he rules the United States like noone before him, with Centuries being the potential length of his political rule.
Eventually the United States restablishes contact with the decendants of other nations, and well, as they say... War. War never changes.
Now with that out of the way, I've got two possible ideas for a mod (as this is very rough concept stuff, I thought it was better here, than in Mod as I'm not actually building the Mod at this stage, I'm discussing story).
The first is at least at the start a rehash of Fallout 2 or Fallout 3's second act, its a GECK-fetch. You start in Vault 8. The vault, having to be resealed rather hastily as the mutants approached is definately not operating within Vault Tec guidelines. As the dwellers needed to retenter the vault well before the start of "Fallout 2" in the "core timeline", the residents are less exposed to radiation and are not infertile (they may however be less fertile). As resoruces run low and the outside world looks safe it has been decided to set up a comittee (which after all is what Vault City did best) to examine reopening the vault and restablishing Vault City. One Problem - Vault 1 only had a single GECK, and its long since been used. You're sent off to go and retreve one, with the inital clues being that there is three in V13 (but you don't know the location - have to stay true to what F2 established what was in the Vault Computer), and the location of Vault 15.
Most of the game is really about learning the differences between the two worlds - travelling through the wreck of Vault City and Reno on the way to V15, seeing old familiar sights, and trying to piece together what happened differently. The game would use a node based method with your VVIT (Vault Tec Vocal Intergrated Transport a Car that you "Talk" to) to travel between nodes. Random encounters would be a design goal similar to the caravan encounters in FO2 - No world map, they just randomly happen.
Eventually you'd get to V15, download the V13 location, and head there, where like in FO3's second act you're forcibly taken by the enclave as you get your hands on the GECK. This ends act 1.
Act 2 would open it out a bit, and take off the rails, opening up Mariposa, Navarro and Vegas as locations - I haven't fleshes this bit really at all it would boil down to 4 main endings:
Destroy the Enclave as a force (thus protecting your people).
Negotiate to have your people annexed by the Enclave, believing it would protect them (of course it won't - you become little more than slaves. A tragic, if deserved ending to the VC people),
Get some leverage on the Enclave to live in peace, separately.
Follow the Enclave's propaganda and exterminate V8 as a threat to the new America (and be rewarded with your death - You're still a mutant in the Enclave's eyes).
Option 2 is to focus on New Vegas' area - possibly less work as the same maps could be used with only minor changes. You're a vault 21 Dweller, and House has just come a-knocking and evicted you all.
I've not got a lot of ideas on this one, but it seems like a one act game with three possible endings -
Take your people to some promised land (and ensure your independence against house/enclave)
Take the vault back - you could play him for it (but you'll need to amass a lot of resources to get him interested, an opportunity for an "empire builder" character?), or simply kill him (getting into the Lucky 38 is going to be a stretch).
Get houses' attention and become his apprentice.
In the meantime, if you're trying to get the vault back you're going to have to take steps to stop house trashing your vault.
Anyone got any other ideas or suggestions?