War Plan Crimson is a pseudo-historical simulation game depicting a hypothetical invasion of Canada by the United States of America in 1935–39, based on the actual "Joint Army and Navy Basic War Plan Red" drawn up by the U.S. government in the 1920s. War Plan Crimson is designed for two players, one representing the leader of the armed forces of the United States that could be deployed against Canada (the US player) and the other representing the commander of the Canadian and British forces that would defend against a foreign invasion (the Commonwealth or CW player).