Just some goals that I'd love to achieve either on my own or with a group.
An instructionless game. Needs a very good story, and a mechanic to pull the player into the game universe.
Reproduce the "magic" of an immersive theme park (DisneyLand / WDW/ Epcot) It really needs to be entirely immersive in order to make it work. Not "Six Flags-ing" it. It has to not show any of the connective tissue.
Integrated game world. Combining multiple different kinds of games in one universe, on one playfield. Fly over a city in a flight sim, create the city in Sim City, drive through it in Burnout, Walk around it in Doom, etc.