Northcott's Nim

A two-dimensional descendant of Charles Bouton's 1902 game of Nim. Each row is a track with your counter on the left and the computer's counter on the right. On your turn, pick a row and slide your counter any number of squares toward the computer's — you can never jump over it. Depending on the rules you choose, either the last player able to move wins, or the last player able to move loses. Under the hood, every row is a Nim heap in disguise.