Tumblingdown is a fast moving stacking game played on a checkerboard,
using more than the standard number of checkers. Your opponents
tallest stack is his "king", and your goal is to capture his king by
capping it with one of your pieces.
Tumblingdown was invented as an entry to a game design contest.
It was a finalist in the contest, but afterward was promptly
forgotten. It came to my attention
when someone pointed out the similarity of the move style to Exxit.
Robots: Too tough
to beat reliably.