Over the years I've been drawn to the idea of an incredibly crunchy, rules-heavy game that remains fun to play and fast to resolve because all the complicated bits are handled in the background by a computer. We've seen a few attempts at augmented gaming apps in recent times, and there might be some really good examples of these that I'm not aware of, but on the whole most of them seem to consist of dice rollers and card simulators, where the outcome then needs to be fed by a human back into some kind of procedural generator.
There was an automatic dungeon generator and explorer I was addicted to for a few weeks. It might have been Dungeon Robber (edit #1: it's the closest I could find while I was in a hurry writing this...edit #2: going back through my blog history, yes, it was Dungeon Robber). That's the kind of thing I'm going for, but more as an open ended town than a dungeon...and with the scope for adding a few players to the adventuring party. It wouldn't need multiple players and could certainly be a good time filler with a lone person on their computer, but I think the potential for multiple players would take things to a whole new level.
I also liked the way characters were saved as a coded string of digits in that game. It means there is no need for back end tables, and server side storage issues.
As a part of a university assignment, I've generated a site called "The Abandoned City" over the last few weeks. It's designed as a gamified learning environment, but could easily function as the basis for an open exploration sandbox in this online rpg tool that I'm considering.
No specific plans yet, just lots of ideas swirling around in the primal soup.