Well, maybe more like 5 hours then. I really think a one or two dungeon RPG would be very do-able, and perfectly bite-sized for RPGamers whose schedules have constricted.
I mean, I don't see that RPG's are necessarily about long term effects. They're fantasy stories, and these could be as short as a single quest, as most fairy tale fantasies are. Also, it's the fantasy setting and focus on the characters local, personal dilemmas that drive these stories, and that can be done in short story length or novel length. If you still wanted long-reaching themes, then these could be threaded through many mini-RPGs that take place in the same world with re-occuring characters at different times in their lives.