I want an involved and evolving game in a non-linear sandbox setting. I guess this could be done with a group but I'm pretty sure it would much harder to maintain consistency. I already have the world developed (pretty much anyways) and just plan to let my player run wild. I expect a lot of improvisation, which is something I excel at, and I expect my player will riff along with me into some pretty awesome new territory.
I think I am going to use heavily modified AD&D 1e with some world specific races and classes. The magic system is always my Achilles heal because, unlike a lot of older gamers, I hate the Vancian style of magic and D&D's magic system in general. So I am going to have to come up with something I like.
If anyone out there has any ideas for me feel free to comment, I am open to any suggestions.