Oculus Rift support would be quite something
Here's a snazzy-looking trailer for the indie game Fract, described by its creators as "musical exploration" game which is currently on Steam's Greenlight service. It's got some of my favorite things in it: abstract visuals, neon, and synthesizers. Lots 'n' lots of synthesizers.
The trailer shows an in-game music creation hub called The Studio which seems to have a fully fledged snyth module and other music creation tools. It looks and sounds great and it's interesting to note the top comment on the video asked for Oculus Rift support. I'll second that motion.