For the last year I've been working on a small RPG, called "AfterZhev", that runs on a single ATmega2560 plus some passive components. The game runs at 60 FPS on a stock 16 MHz ATmega2560, so it's Arduino Mega2560 compatible, and generates a 60 Hz 640x480 VGA video output, with an effective resolution of 120x66 pixels. It also generates 8-bit sound. AfterZhev was written entirely in AVR assembly.
AfterZhev - I think! - is the only graphical RPG that runs on an 8-bit Atmel chip. I'd like to be wrong about that, though.
As the world's official best player, I can beat the game in under three minutes, but it'll probably take an hour or so to complete. Let me know what you think!
Writeup: https://thcopeland.com/projects/afterzhev
Source code: https://github.com/thcopeland/afterzhev
Here I was, happy to have finally made an N64-to-USB adapter, roughly 15 years after I bought the parts (ATmega32 and the cheapest programmer money could buy at the time) :)