A Zach-like with music synthesis as the core mechanic. I still think it's a good idea, but I don't really know how to write fun games (I think you have to write one or two to get enough experience) and I do know how to write 2D renderers, and increasingly feel able to claim I know how to program GPUs as well. I think it was Ivan Sutherland who said a good plan for research is to do something you think is easy and other people think is hard.

That's a pretty neat idea! (Though probably hard as hell to design...)