Nine men’s morris is a strategy board game for two players. It is an ancient game, dating back to at least the Roman Empire.[1] The game is also known as nine-man morris, mill, mills, the mill game, merels, merrills, merelles, marelles, morelles, and ninepenny marl[2] in English. In North America, the game has also been called cowboy checkers, and its board is sometimes printed on the back of checkerboards. Nine men’s morris is a solved game, that is, a game whose optimal strategy has already been calculated. It has been shown that with perfect play from both players, the game results in a draw.
There’s a really good rendition of the game available in the Debian/Ubuntu and Arch repos simply called Morris (available for Windows there, too), hopefully it’s available on other distros repos as well. Though if not, there’s a bunch of renditions of it available online.
There’s also a more advanced version from Africa called Morabaraba
Oooo, this is harder than it looks.
The app I linked to seems like it may be particularly hard, and according to description even learns from past games. I’ve yet to beat it myself.