On par of Microchess https://www.benlo.com/microchess/index.html https://www.benlo.com/microchess/index.html and Nanochess https://nanochess.org https://nanoche

On par of Microchess https://www.benlo.com/microchess/index.html https://www.benlo.com/microchess/index.html and Nanochess https://nanochess.org https://nanochess.org from Óscar Toledo. Microchess has a C-port with an emulated MOS 6502 inside. That's it, you are actually simulating a barebones Kim-1 with Microchess as the bundled "ROM" already in RAM. I might port the C port to its transputer with Micro-C if I'm bored.