Isn’t that the plot to Grey Goo: New Vegas?

(on more further consideration than I can reasonably justify, I think I’ve come up with an…um…super convincing explanation for why there would be a ‘New Vegas’ after a grey goo incident, and what other plot elements would exist: Presumably if one were creating self-replicating shuffler robots, one would include a feature to ensure that the robots replicate as efficiently as possible by recognizing other robots of the same type and not wasting time breaking them down and re-replicating them, when the job was already done at least once.

If that is the case, locations on earth with extremely high concentrations of card-shuffling and similar machines already, notably the great casino-clusters of the world, would be overlooked during the unstoppable proliferation of self-replicating cardbots, known to survivors as “The Big All-In”. In Vegas, The Strip, and a few of the outer zones, would be spared for this reason, with a mixture of locals and stranded tourists in a world where, suddenly, what happens in Vegas stays in Vegas, because there isn’t anything outside, except rumors of ‘Macao’ still existing and a few offshore gambling boats that quickly descended into cannibalistic insanity, run aground on a slurry of self-replicating robots.

In what remains of Vegas, the Nevada Gaming Control board, the only entity with expertise in gambling machine programming and access to state violence steps in as the guardian, and government, of what remains of civilization. At the edges of the city, and in the wasteland, “Players”, rogue experts in machine manipulation indulge in the risky game of code-jacking ‘live’ nanite to insert their own directives. It’s a dangerous business. Most newbs are simply swallowed up and now shuffle cards with the rest of the earth’s crust. Sometimes an expert slips up and a more…twisted… fate befalls him (The player they call ‘The Joker’ is a living legend; but even he hasn’t been able to reverse what happened when the nanite he was 'jacking got out of control and reconstructed much of his body based on the templates for one of the deck’s face cards.) However, the risk is matched by the reward; because in a world whose industry, agriculture, and entire economy, save only hookers, gambling, and novelty restaurants was annihilated within hours, “tame” nanite is the most precious commodity there is, and a talented and lucky player can make a fortune supplying the city with this invaluable resource.

Within the city, of course, you have the former entertainers and casino operators, hustling to be the ones who get the job when a player makes good. You’ve got the Gaming Control board, which views the players as dangerous, liable to accidentally destabilize the grey goo and end things once and for all; but in no position to crack down too hard on people so vital to civilization. Adding to the general in-city atmosphere of mayhem and confusion, the destruction of almost everything that isn’t Vegas obviously rendered

Organized crime was there before the Big All-In, and some of it hangs on, trying to keep a finger in what pies remain. Some are merely crass and greedy. Some may be playing longer games…

On the edges of the city, where occasional nanite breakthroughs make things tenuous, you have the desperate and the idealistic. The bankrupts, the people who lost it all, the players who got burned (or worse), and the ‘reclaimers’ who use improvised camouflage barriers constructed of neutralized shufflers to ‘hide’ plots of land, and a combination of thermal destruction and whatever tame nanite they can beg(some players are mere mercenaries, some do have better natures, better even than one might expect, some are inscrutable; but are as likely, when they come to town, to give away an unimaginable fortune in tame nanite as they might be to deliberately breach the barriers without apparent reason and be taken down by Gaming Control, you just never know), borrow, buy, or steal to cleanse the ‘hidden’ plots and create arable land, industry, or other attempts to rebuild what was lost.

There are also groups you would be less advised to try to reason with: The various ‘stochastic Millenarian’ cults believe that the present hellish state is irredeemable until the last permutation has been dealt, and the planet redeemed, at which point the shufflers will cease their work and restore what was before. The (rare) agreement between the Gaming Control Board and the Players that the shufflers contain no such reconstruction code has failed to dampen their enthusiasm; but their passivity in waiting for the restoration has them viewed as largely harmless.

Unfortunately, not all the more shadowy cults that flourish in this environment of extreme dislocation are… against… the prospect of the final success of the shufflers and the hastening of their eventual success. The most open(but most controversial) of these is led by ‘The Player of Games’, a figure of undoubted brilliance, among the earliest and greatest of the players, who commands more nanite than almost anyone and plays a very ambiguous role: rumors of his association with the more extreme cults are too numerous and credible to deny; but (unlike some of the duller cultists) he is well aware that Earth doesn’t have enough time to complete the shuffling, whether or not a few extra cities are added, so his interventions have, so far, been overwhelmingly benevolent, if possibly in the direction of spreading even more virulent shuffler nanite beyond the planet and to the stars.

I don’t know exactly how a player-character would fit in; but that’s my general conception of Grey Goo: New Vegas.)