Greetings All,
Sorry to butt into the conversation but I saw 'Alternate Universe' and thought that was right in my area.
Alternate Universe or Parallel Universes or Alternate Realities or any such term you'd prefer are very common around here as many people myself included like to write Fan Fiction novels or Role Plays that include elements beyond the canon material.
For instance I know @Flamebiplane is writing an RP that includes steampunk technology. @The Reptile King has an expansive world called the Reptile Kingdom, @AngryLance is building a farming town called Mirefield with surrounding settlements.
(They've put a heap of effort into their stuff so certainly worth a look.)
I'm writing my own story in a Parallel Universe because I didn't want to be constrained to the setting. I have postmodern technology such as Starships and Space stations since I wanted to do a time travel story across many worlds. And Mamono and Incubi are Immortal since I'm using a Time Lord character. (Didn't want him to be the oldest character eh)
My point is you can do anything you can think of with this setting, the narrative is conducive to change and experimentation, it's even highly encouraged to create your own spin on things. So long spiel short yes AU's are highly thought of in these circles.
Cheers,
The Weary TimeLord.