Super excited about the progress I've made on this. It's an ESP32 based battery powered handheld game console designed for one game and one game only: Tetris.
It uses a "cheap yellow display" as the brains and display, and GBA buttons thanks to a neat GBA button PCB set I found on AliExpress. I think the PCBs were destined to turn a GBA shell into a controller but it's perfect for this scenario.
I've programmed a pretty faithful "guideline" style Tetris with hold, 7-bag randomizer, SRS rotation, hard drop, ghost piece, etc. T-spins are recognized and there are separate high scores for marathon (150 lines) and endless. The progress bars on the left are for marathon progress, and level progress. (Not totally necessary but that part of the screen would otherwise not be used!)
The single shoulder button uses a tact switch meant for a Logitech mouse, since I had a few on hand.
The whole thing runs on a Nokia battery and gets around 6 hours of battery but I need to do some more testing. You can charge the battery by sliding open the battery door and popping it out into a charger, or using the onboard USB C port. The battery level is displayed in the window on the lower right.
There's no power switch but you can deep sleep the ESP32 and wake it up by holding start + shoulder button. Seems to use very little power in sleep mode but I take the battery out of storing it long term.
The shell was custom designed in Fusion using a 3D scan of a GBA shell to make sure the buttons and D-pad work.
Everything is made using off the shelf parts from AliExpress, no custom PCBs or complicated soldering required and I'll be posting the files and parts list soon!