Martian Tic-Tac-Toe is an Icehouse game for 2 players played on a 3x3 square board. Each player starts with a stash of three small pieces, three medium pieces and three large pieces, all of one color. On each player's first turn, that player must place a small piece into a square. After that each player may make one of the following moves: 1. Place a small piece from your stash into an empty square. 2. Swap one of your pieces in play with a piece from your stash (up to one size larger or any size smaller). 3. Capture an opponent's piece by replacing it with a piece from your stash exactly one size larger and sending the captured piece back to the opponent's stash. A player wins when they get three of their pieces of the same size in a straight line (orthogonal or diagonal).