Instructions:
Set out 12 rocks ( or other objects) so that there are three rows with 3, 4, and 5 rocks in each row. The goal of the game is to make the other person take the last stone. Each of you take turns removing stones from the rows. Each turn you may take as many stones as you want from one of the rows.

Hint:
There are 5 combinations that you can create so that you are guaranteeded to win.

Misc:
I could see this as a great game for students to play to help them develop their logical skills. I'll try to create a printable lesson plan & instructions for this soon. Unfotunately I can't claim that I created this game. I learned about it while I was at my brother-in-laws wedding this last weekend, a guy from Austraila named Luke showed me it to me. He didn't have a name for it so I'll just call it twelve rocks.