Chess is a hard protocol. Don’t let the balloon touch the ground is a soft protocol. Both constrain action; one is digital and one is analog.[1] A stickler for the rules spoils the fun: they insist that the play of a game is a performance of the rules.[2] Everyone knows that the NBA is more fun because referees beings get the play to interpret the rules. Play has less to do with protocol, and more to do with constraints that enable play, play that transforms the constraint into proposition.
[1][1] Gilles Deleuze and Felix Guattari write about this distinction in terms of “smooth space” versus “striated space”. Chess occupies a striated space, not just because of the grid of the game board, but because the roles and functions of the pieces are fixed. The Chinese game Go, on the other hand, while also using a striated game board, functions in a smooth space because the function and possibility of the game pieces are reconfigured according to their spatial and sequential relationship to other pieces on the board (A Thousand Plateaus, Treatise on Nomadology).
[2] See Ian Bogost’s concept of “procedural rhetoric” which he writes about in the concept of games.