While reading Hacker News Sunday morning, I am across a link to this Ruby programming game called Ruby Warrior. On each level, you write ruby code, run it, and watch the results play out on the screen.
The game calls your method "play_turn" passing in an object that controls your character. I've printed out the code to pass level 01.
# cool code goes here
It even has a 80's style sound track to go with the 80's graphics.