My port of Doom for the Thumby is now available on
github.

Installing it is a bit of an adventure, and it will overwrite the firmware & games on your device. There are two files in
Releases that need to be installed; the game itself is a .uf2 file, but the data needs to be installed using picotool.
The port is based on RP2040 doom, but modifies it to work with the Thumby screen.