I was honored to win the Twitter RPG Design Competition for a simple game of intelligent weasels:
"Play intelligent weasels with other beasts in forest. 13 points in Sneaky, Vicious, Persuade, Health. Beat 1d6 to succeed; 1 damage per hit."
This so thrilled me that I put together a one-page PDF, describing the game in more detail. In Weasels, you play an intelligent weasel who lives in the Woods, and has banded together with a few brethren to face a Problem.
The system is based loosely on GURPS and Mouse Guard, of all things.