Chinese Dark Chess

Chinese dark chess is a popular and easy-to-learn game in Asia. The characteristic of possible revealing of unknown pieces makes it different from Chinese chess or Western chess. Players with luck may win a game by chance. Thus, there is a probabilistic behavior that a player has to consider. Computer Chinese dark chess problems can be divided into three phases: 1) the opening game, 2) the middle game, and 3) the endgame. Revealing pieces reasonably and effectively is the main issue in the opening game. In the middle game, the choice of revealing pieces or moving pieces becomes the critical issue. Designing a good evaluation function is also important both in the middle game and endgame. In an advantageous endgame, how to capture all opponent’s pieces to win the game is also a hard problem. Search-based methods, such as αβ pruning, are only suitable in the positions where revealing actions do not influence the results. However, according to our experiments, programs that reveal pieces reasonably and effectively have better playing strength. In this paper, we introduce the game Chinese dark chess and give some research topics about this game. We also discuss some strategies for considering the revealing actions in this paper.