Simple Sunday Game Design

David McDonough recently posted his 20th "Simple Sunday" Game Design. Every week, he posts a design for a new game that adheres to the following rules:

1. The entire description and ruleset must fit on one page (more or less).
2. No extravagant or custom objects, including cards, tokens, boards, or other devices.
3. Try to be original; keep it simple.

I haven't read through all of them, but he's recently been doing ones where the board is a piece of paper, and the players battle it out in some way by drawing things on the paper. Check out the interesting games Molecule, Hardscrabble, and Penicillin. Many of these are designs that haven't been playtested yet, so feel free to play them and then give him some feedback.