This is my lazy entry.
It fits the theme only barely.
It is a block breaker game (known in Japan as "block kuzushi") type game inside a music editor software.

• The editor itself can be considered an obscure platform
• Notes of varying colours and sizes are used for all the graphics which could fit procgen or geometron
• The "music" is in fact generated by gameplay
• More interestingly it allows a microphone as an input device

More on the last item:

Although the game can be controlled with regular mouse-based editor actions (moving the paddle note), optional audio input can be used. Lower pitch (lower frequency) will move the paddle left, and higher pitch (higher frequency) will move the paddle right. The interval must be calibrated by the user. Thus the user can sing or play an instrument to control the paddle.

The pitch detection is based on Harmonic Product Spectrum technique.

There is however an enormous issue in the form of large latency. This is due to soundcard/OS level issues but also due to the used library having non-configurable capture buffer size. In my machine it picks 1-second sized buffers, thus causing as much as 1 second of input latency. "Reduce lag" option will use only the end of the buffer, which will make the game slightly more responsive.

I am a remarkably poor singer, and I was unable to actually play the game with voice control (I could at most move it consistently to either left, right or randomly inbetween). With a toy keyboard the paddle was consistently controllable (but the latency still made the game almost unplayable).

The editor

I call the editor Nuklear Powered Piano.
It is a simple music editor initially inspired by https://onlinesequencer.net/ I have been making.
It supports MIDI files, MIDI output, sample-based instruments and has an embedded Game Boy emulator for chiptune instruments. Soundfont support is still WIP.