In a slightly safer departure away from jetpack roller-skating and flinging around bolts of lightning, [Ian Charnas] has been hacking retro video games. After a lot of hard work [Ian] has managed to add pose estimation to control the character in the NES boxing game “Punch-Out.” Surely he can’t get hurt doing that? No, but since it wasn’t fair to hurt the poor suffering characters, without taking any damage himself, he added electric-shock feedback to give the game a bit more, ahem, punch. See, you can get hurt playing video games!

By starting with Google MoveNet, which is a pre-baked skeletal tracking model which can run in a browser using TensorFlowJS, he defined some simple heuristics for the various boxing moves usually performed with the game controller. Next, he needed to get the game. Being a all-round good guy, [Ian] bought an original copy of the game cartridge to obtain the license, then using the USB CopyNES from RetroUSB, dumped out the game binary for the next step.

Emulation of the NES hardware was chosen, taken care of by FCEUX, in order to run the game and the posture model on the same machine. This simplified the control of the game, since it would be somewhat more work to have it run on the original NES. By using emscripten, FCEUX was cross-compiled to WebAssembly, and so both the game and control side are both in the land of JavaScript. To be honest, after playing the game a little, [Ian] found it far too fast to be playable with posture control, as opposed to much faster button pressing, so some game hacking was required. Emulation made this much easier.

It took [Ian] around two months of disassembling the game binary, and figuring out the game logic around the characters in order to slow them down enough to make it playable, but he did manage it. You can be the judge, since he bought a bunch more cartridges to unlock more license copies, you can play it too. Just don’t add the electric-shock part, nobody needs to be administered electric shock therapy from a two inch high bright orange Mike Tyson!