https://www.youtube.com/live/v4uHqdTr-bs?feature=share&t=426...
There are a few simple but powerful building blocks. One main feature is an egg shaped "note" which can be placed, resized, retuned and cloned on the fly. It's played by physics interactions with a "mallet" or sports balls, anything with a collider.
One of the instruments is a sine wave organ which has drawbars to control the amplitude of overtones. Unlike a classic organ, these overtones can be independently retuned and assigned envelopes to produce a range of timbres. Pitch is consistently mapped to a spiral - an isomorphism of pitch space.
It has a theremin which provides visual and tactile feedback and a voice with vocal formants controllable with a thumbstick.
It has a physics based sequencer of sorts which consists of "mallets" on a wheel which spins at a desired ratio of whatever BPM is set in a DAW. These wheels can be cloned and multiple mallets arranged around the circle using the Euclidean rhythm algorithm.
Since low latency audio in Unity is tricky, the VR app is really just a controller for synthesizers running in Max/MSP and IEM spatial audio VSTs running in REAPER. One day I'd like to package some portion of it into a mobile VR app for things like remote jamming or music lessons where models of the theoretic ideas are right there in front of us to tinker with. For now, it's just for me.