There are fewer alternative world films than you would expect. Well, than I would expect. But frankly if I made films (or TV series) they would all be set in alternate worlds. I mean, if you are going to all that expense, the marginal cost of the imaginary world cannot be that much more. I have long lobbied for EastEnders set in a world where the Germans won WWII, though actually maybe a world in which the General Strike lead to a revolution (*).
(*) there is a Mat Coward detective short story set in such a world. If only the full length alternate world detective novel I read had been by him rather than Jo Walton.