Okay, to the people crying for Fallout: London... why just London? I'll explain.
In America, they think a hundred years is a long time, but in Europe they think a hundred miles is a long way. In the context of the Fallout series, that means they don't have to put in a fast travel mechanic simply because the distances involved are similar to those the average Vault-dweller'd go to get a bottle of Nuka-Cola and a packet of crisps. London's a fantastic starting point, especially for foreign gamers who don't know anywhere else and have recognisable (if a bit knackered) landmarks, but what about the rest of the country?
You could make the Black Country, well... black: break open the coalfields and turn Sheffield into the British version of the Pitt, all grey factories and half-destroyed council estates and coal-lunged miners desperately warding off their irradiated former fellows with picks and the occasional salvaged rifle.
The West Country is perfect for the Bayou-esque sections, only marred with poison rain and inbred yokels slowly going mad. Have horrifically mutated badgers and foxes and so forth becoming real-life Beasts of Bodmin, coming in the night as a killing mist descends, rending the unwary in two under the baleful gaze of uncaring moonlight.
To the east, we could have a proper turf war going on; crazed hyperconservative technologists from the remains of the London satellite towns fending off desperate, Chelsea tractor-mounted raiders from the doubly-irradiated Kent coast and shambling, zombie-like mutants from the flooded, radiation-filled near-wasteland of the Fens.
And that's just England. Wales would be similar to the West Country in execution, only even weirder and with mutated feral cats prowling Snowdonia and locals who are no longer content with setting wrecked English holiday cottages ablaze but now extend the offer of terminal heating to you, gabbling away in an incomprehensible language of their own devising. Called Welsh. The Scottish Lowlands might be vaguely okay, but they'd be predated by super mutants from Aberdeenshire. Similarly to Cornwall, up there it's all granite so they were radioactive anyway, even before the bombs fell, so they'd have barely any humans up there - all ghouls and muties.
As for Ireland, well... the Troubles, I reckon, never went away. So you've got an entire island full of screaming, bloodthirsty mutants wandering around armed to the teeth... and the Republican half has more, so they'll win. And then they're coming for the mainlanders.
Read that, honestly read that, and tell me that's no worse a set of ideas than the ones for the American Midwest. Australia, now, that'd be an amazing game, but Kansas? What the hell do you expect the player to face there, mutant cereal crops?