Gamehelpyonkoma

INTRODUCTION

Yonkoma is played on an even sided, square checkerboard, oriented with a dark square in the bottom left corner. The two players, Red and Blue, each have two checkers. Red's checkers start on dark squares in two diagonally opposite corners. Blue's checkers start on light squares in the other two corners. Figure 1 shows the starting position on the 6x6 board used in the figures. The players take turns moving their checkers, one checker per turn, starting with Red. Passing is not allowed, but if you don't have an available move, your turn is skipped. Cycles and deadlocks cannot occur in Yonkoma. Mark Steere, in collaboration with Claude, an AI model made by Anthropic, designed Yonkoma in October 2026.

PLAY On your turn, move one of your checkers any number of squares along a diagonal, as a bishop moves in chess. A checker cannot pass through or land on another checker.

LEGAL MOVES The distance between two squares is the number of king moves between them. That is, it's the larger of the number of rows apart and the number of columns apart. Your move must do one of two things: 1) bring your moved checker closer to the two enemy checkers, so that the sum of its distances to them decreases, or 2) leave that sum unchanged and move your checker farther from your other checker.

OBJECT OF THE GAME

A crosscut is a 2x2 block of squares holding all four checkers, with the two red checkers on one diagonal of the block and the two blue checkers on the other. Whoever completes a crosscut loses.