Picking this as my second attempt at an AI game turned out to be a bit overambitious since it suffers heavily from combinatorial explosion. It's playable if you're willing to wait about 3 minutes for the server to move.

Focus for two players

This is a game designed by Sid Sackson which I found in his book A Gamut of Games.

It was designed to be played with stacked poker chips or checkers counters which need to maintain their order, which I've represented with rectangles.

First player is determined randomly. In their turn, players can move a pile of pieces where the top piece is their colour up to as many spaces as there are pieces in the pile. Piles move in a straight line up or down, left or right (no diagonal moves in this game). If a pile moves less spaces than it has pieces, it leaves some behind in the starting space. The moving pile is as big as the spaces it moves.

Piles can't get bigger than 5 pieces. When a pile ends it turn with more than 5 pieces, those excess pieces of the player's colour go into the offboard reserve while the opponent's pieces are eliminated.

Once players have reserve pieces, they can place a reserve piece anywhere on the board instead of moving a pile in their turn.

Victory is when the opponent can't move: ie there are no piles on the board with their piece on top and they have no reserves.

There is a also a 4 player version of this game which sounds similar to this version in that partner teams of 2 players compete against each other.

Board Games Geek has a page giving more info on this game, including that it was the 1981 Spiel des Jahres Winner.

I started threads on Board Game Geek and Reddit's gamedev for anyone interested in discussing the game or my DIY browser-based strategy boardgame framework.