This year was my first year attending IndieCade and I was fortunate enough to sit in on some wonderful panels! Among them was Jeremy Gibson's game design workshop, which he has graciously posted slides for at his site http://jrgibson.net/. As part of his workshop, we played a simple card game. The basic idea of the game is to place an allowed card from your hand on top of the center pile whenever it's your turn. If you cannot place a card, you draw a card. First to lose all their cards wins.
After getting an idea of how the game feels and plays, we were asked to change one rule of the game and analyze the results. I was actually really surprised to see how dramatically one simple rule change could affect the game's mood. Rules that affected the rotation made players feel a loss of control, while rules that allowed players to benefit from punishing other players made the game more aggressive and fast paced.
This made me wonder what some universally simple games would be like if you added one simple rule. I decided to try this with the classic, and usually quite boring, tic tac toe. In tic tac coe, the board fills up quickly and the game ends whether or not someone has won. To combat this, I added one rule: each player only gets three marks. In other words, when you place your fourth mark, your first mark is removed so that you can only have three on the board at a time.
I built a quick two-player prototype in HTML to test this out. I quickly noticed a few differences: the game is obviously longer as the board does not fill up, there is added strategy in anticipating where the spaces will clear up, and extra challenge in memorizing the order that marks were placed. Players not anticipating the need to focus and memorize the order would become frustrated when they place their connecting mark and another mark in the winning row would disappear.
The game is available to play here. I encourage you to try it out, and please let me know what your reaction was!