Stacksmashing has just posted a video, summing up the current status of Game & Watch hacking. There’s been a ton of work already completed, such as fully reverse-engineered schematics, a replacement memory chip to allow more games to be stored and even X-Ray’s of the PCB!
The community has taken things one step further, with the release of a 3D printed rear shell that allows easy access to the programming port without the need to cut the original. People are also looking into a mod that integrates an ESP32 WiFi module, which could lead to things like wireless transfer of ROMs. Work has even begun on a full PCB replacement that includes an FPGA that can run a NES core!
The software side of the current board’s jailbreak is progressing nicely as well. They’ve implemented a menu to select your game, as well as options like interpolation, so games can fit the full width of the screen without shimmering. There’s also work on emulation for the original Game & Watch games, which would obviously be a prefect fit for this device!
Unfortunately, the hacking process itself it still a bit complicated and requires using a debug adapter and some custom wiring. Full guides for both the hardware and software process are available here: