Doom Running on a Game & Watch

Game & Watch is a legendary name among Nintendo fans. The first units of this series date back to April 1980, and anyone who owns one in good condition has a virtual fortune in their hands. Recently, Nintendo introduced an updated version of the Game & Watch, which was hacked a day before its release, and as expected, the Web only asked for one thing: to see Doom running. YouTuber “stacksmashing” decided to give it a try, and although his final version received several adjustments, I think we can talk about mission accomplished….

Yesterday it was a simple demonstration of curiosity. Today, it is the definitive “Hello World”. Of course, I mean installing and running Doom on anything that can receive it… and others that need a little help. We have everything on the list: thermostats, ATMs, printers, calculators, oscilloscopes, and even pregnancy tests. Every time we think of some limit, enthusiasts come out with something different, and this time they took advantage of a new “classic console” from Nintendo.

I refer to the Game & Watch “2020 edition” with color screen, Super Mario Bros. and Super Mario Bros. 2 (that is, “Lost Levels”) preinstalled. Logically, the device seeks to seduce collectors and hardcore fans alike, but if at the software and hardware level it behaves like a retro console emulating NES games, then only one thing remains to do: replace the original firmware and place a copy of Doom inside.

Doom on the new Game & Watch

That was exactly what the YouTuber and hacker “stacksmashing” did, who received one of the new Game & Watch and managed to hack it one day before its official launch . Luckily, Nintendo did not cover the entire PCB with epoxy, and there were no major problems identifying the STM32H7B0 controller (ARM Cortex-M7, 128 kilobytes of Flash). However, Nintendo activated the security mode on the chip, so stacksmashing had to break the encryption first. The good news is that Doom seems to run without hitches. The bad news is that it is a reduced version.

Why? Because the Game & Watch does not have enough resources. In total it combines 128 KB of Flash and 1.3 MB of RAM in the controller, and barely 1.1 MB of external Flash. The solution was to extract textures and other secondary elements from the game (courtesy of the MiniWAD project), but the essence of Doom is there, and it works well. What comes next? Probably a method to load other ROMs into the Game & Watch and complete its transformation into a portable retro console. A matter of time.