“A key issue from the outset was whether it was better to codify the game system within comprehensive rules and charts or to base the modelling of movement and combat on the wisdom and experience of an umpire.”
— Philip Sabin, Simulating War
Early wargame rules established two acceptable play formats: rigid and free. When military personnel started creating wargames in the early 19th century, an umpire or even a team of referees adjudicated wargame conflicts. Those in the “rigid” style adhered to carefully crafted rules governing many, if not all, possible actions and contests within a game scenario. The referee served as a knowledgeable intermediary, someone so immersed in the rules as to function as a reference when applying them consistently during play. This allowed players to focus on the action depicted on the wargaming table from the perspective of officers commanding troops in the field, much as they’d been trained. Those in the “free” style relied on their own military expertise and judgment to interpret the situations on the board, possibly also with some institutional doctrine and perhaps loose guidelines regarding conflicts on the battlefield. Free kriegspiel relied on an expert’s informed yet subjective opinion rather than established, comprehensive rules. As wargames evolved they branched in several directions, including professional and hobby as well as rigid and free. Free games continued to exist — especially in the military sphere or exercises like matrix games — but most games, especially in the growing hobby, skewed toward rigid. We can look at games in our own time through the lens of rigid and free play...but they primarily sustain the trend toward the rigid end of the spectrum.