I'd be thrilled to thow some cash at a Planescape: Torment style game, though I'd be interested in it for the intricate story, the setting, and the fact that it is D&D based, in that order. If you could somehow start a Vampire the Masquerade: Bloodlines sequel, well I'd throw down double. Not the newer, Requiem based stuff, but the old World of Darkness. That had some seriously deep stuff going on. You could scrap the actual mechanics that WoD uses (the multiple d10 system they use is terribly unbalanced), but I like the themes, powers, and versatile use of skills of the system.