Check out his C64 demo "A Mind Is Born", where he fits a "procedurally-generating" song with visuals in barely 256(!!!) bytes.
Does anybody know any examples?
My uneducated guess is that perhaps the thing of the day now is proper voxels (not Minecraft's “voxels”) and lots of shaders on top. But then again, this endeavour doesn't really differ from just making experimental game engines.
I don't think it uses any fancy modern CPU features but this is probably the reigning champion of the 256 byte demo, and its write up[0]
I think it is this limiting factor that is partly responsible for keeping the C64 scene alive. While it is limiting, there are also still infinite possibilities of creativity. I don't personally find say, the PC demo scene as interesting because it is not really limited in any way other than size competitions. But still there you get a lot more mileage out of every opcode than on the C64.