The Chessmaster is a long-running series of chess video games made for various consoles and computers. The Game Boy version of the game comes with various ways to tweak the CPU opponent, such as allowing it to think while you make your move and whether or not it has access to a predefined set of moves to make early on.
Walgrey improves on the previous run by 0.268 seconds by using a Bishop to capture the pawn (the previous run used Queen) that results in a faster time to checkmate the opponent.