So, this idea is kind of a retry, and I have no idea which genre it would fit. So, here goes nothing.

Basically, the idea is that dreams are actually a portal to people's true reality, the true destiny people should have.

The bank clerk can be a powerful warrior, the girl who spends her day selling coffee and being treated like crap can be a beautiful princess, etc etc. Our characters (as many as they are) would be those people.

I still don't have the exact details, but I would like it to be a total fantasy world, maybe something D&D like. Details can vary, but think medieval fantasy, tabletop roleplays, LoTR movies, etc. With the catch that the characters can start by taking personal changes back into the world, and, as they become more involved in the world, physical changes, and maybe even items. Or, at some point, they may choose to stay in dream land.

It would be interesting if they didn't know each other in their waking hours, but did in the dream, but those details can be fleshed out if this takes off.