Design a gamepad's controls in TouchOSC on a phone, send them over Wi-Fi as OSC to an ESP32-S3, and let the ESP32-S3 present them to a computer as a USB gamepad: the computer sees a gamepad, and the player plays a layout of their own.

The Bluetooth sibling of the Wi-Fi recipe: design a gamepad's controls in TouchOSC on a phone, send them as MIDI over Bluetooth LE to a board built on Nordic's nRF52840, and let the board present them to a computer as a USB gamepad, with no Wi-Fi network in between.

Pull strings instead of pressing keys: a row of long-lever microswitches, each worked by its own string.

A keyboard and mouse adapter lets a console take a computer keyboard and mouse in place of its game controller.

Rebuild the Stylophone in conductive paper: a keyboard you play with your fingers, a paper pressure sensor for vibrato, one microcontroller, and a pizza box as the sounding board.

Play a theremin with Gametrak tethers: one hand's position sets the pitch, the other's pull the volume.

Pin a Gametrak tether along an angled pole to make a plucked, stopped string, like a tea-chest or washtub bass.

A round, upright harp of Gametrak tethers bound by a movable ring, for groups of players from young children to skilled musicians.