A game that plays on an Arduino Mega 2560 using no external libraries other than the standard AVR/Arduino ones. Using my Arduino-VGA code, I decided to make a little Atari 2600 "Adventure" -esque game. Check Arduventure.cpp and Arduventure.h for which pins to hook everything to.
This project uses PlatformIO to build, although if you threw all of the files from include and src into the same folder and renamed Arduventure.cpp to Arduventure.ino it would probably work fine with the regular Arduino IDE.