Comply/Constrain Subtraction

A comply/constrain game or a game with a Muller twist is a game where the next player is allowed to place constraints on opponent’s next move. We develop a closed form formula for the Grundy value of the single-pile subtraction game where the next player may determine whether the previous player has to select a move from the set of some first k natural numbers or its complement. We also investigate the periodicity of Grundy values when the set of legal moves is from a set of finite arithmetic sequences.