Word for someone obsessed with an unreal or alternate universe (eg. trekkie, but in general)?

Is there a general term for someone obsessed with an unreal or alternate universe/reality? Like a Trekkie or someone obsessed with Star Wars, such that they research and spend time philosophizing about that alternate universe/"reality" and maybe even ordering their life around some of those philosophies?

Solution 1:

Escapist -a person who is obsessed with the habitual diversion of the mind to purely imaginative activity or entertainment as an escape from reality or routine.

Link-MW (Definition is modified to describe a person.)

Solution 2:

In America, the word "fanatic" captures well the elevation of a secular obsession.

"Religious", in the colloquial sense works; though if they are obsessed and order their life around it, then an argument could be made for the literal.

"Delusional" seems pejorative.