Audiovisual Playground is an immersive, VR music-making experience. It was developed in Unity for the HTC Vive by Annie Kelly, Kristof Klipfel, Chris Koski, and Alex Goodwin.
Annie Kelly: technopagan.net/
Source code / Unity game: github.com/Singularity3/av-playground
Drumless backing track: drumlessbackingtracks.bandcamp.com/