Thanks to Drew for sharing! Via OSH Park
Jarek Lupinski created this board that uses the actual Sega Genesis sound chips to play chiptune files:
Sega Genesis Native Hardware Chiptune Synthesizer
The VGM file format stores instructions for sound chips, and VGM files for many popular games can be found online. An Atmega1284p microcontroller will read these VGM files from an SD card and translate them into signals to send to the onboard YM2612 and SN76489 chips. These chips were used by the original Sega Genesis hardware to make the sound effects and music in Genesis games.