This may be a lost case… I saw that movie years ago, in early nineties I suppose. Problem is it was polish TV (I think it was in English), so movie could be from 80s or even 70s – no idea. In color for sure.
I remember a group of teenagers playing some kind of fantasy role playing game. At the end of it one of them (a boy) didn’t mentally returned from that fantasy realm. The rest of them visited him (in mental hospital maybe?) continuing to play the roles to please him.
I know it is not much, but maybe someone knows it O.o