A simplified pacman clone I wrote a while ago in assembly, to be run as an MBR. Originally written for the Stripe MBR challenge:
Submit a 512-byte MBR boot sector that does something interesting (the specifics are up to you) and before exiting prints "Stripe".
The easiest way to run is:
nasm mbr-game.asm qemu-system-i386 mbr-game
Overall, this is all written in 482 bytes, including the bytes required for MBR. I wanted to add at least one enemy, but 30 bytes weren't enough for one.
The code isn't heavily commented, especially for a beginner, but routine names should make the functionality fairly obvious. If you are interested in learning, start here: