Cyrus IS Chess is a puzzle game released for the ZX Spectrum in 1971. The story revolves around an ancient king's quest to protect his kingdom from invaders. According to legend, the king was aided by a wise old sage who created a magical chessboard with special powers.
Gameplay involves controlling a knight piece on the board, moving it through a maze of squares to reach the king and defeat the invading army. The twist is that some squares are marked with a symbol that changes color depending on the time of day or season, adding an extra layer of challenge to the game.