A game of balance. Players place wooden blocks on a wooden seesaw trying to get it to tip.
Each player starts with 22 wooden blocks and tries to become the first player to get rid of all their blocks. The blocks come in 4 different sizes (each size is a different color).
On your turn, you place blocks in a single stack on the high side of the seesaw. You have to keep placing blocks until either the seesaw tips or the stack you are building collapses. If you tip the seesaw and then blocks fall off, those blocks are given to your opponent. However, if the stack collapses before the seesaw tips, then you get stuck with any blocks that fall onto the table.
In either case, any blocks that stay on the seesaw are left there to complicate future turns.
Steady hands and a little knowledge of physics helps.