1. Sniderman S. Unwritten Rules. In: The Game Design Reader. MIT Press; 2006:476-502.
This starts with a definition of a game as 'a play activity that consists of an object (a goal or goals that the players are trying to accomplish) and constraints on the players' behaviour (what they must do and/or what they may not do in attempting to achieve the game's object).'
Some of the constraints are explicit (the perceived rules of the game - the sheet that comes with the board game for example), whilst others are not. The author claims that some of the non-explicit rules may actually be impossible to completely define. He uses the example of tic-tac-toe (naughts and crosses!), where the basic rules are pretty simple, but what about a time limit on turn length? If a time limit is specified, then you need to specify how that time limit is measured, and what can interrupt the timer. In fact, trying to write a rule about an explicit time limit draws attention to the fact that it is a potential problem, where most games of naughts and crosses don't have that problem.
The author says rather than explicit rules we have unwritten rules (or expectations) of what will happen and how we will play.
Game officials can also pull and push and make extra decisions about the "real" or written game rules. The author uses the example of a fire alarm interrupting a chess tournament - does the time spent evacuated out of the building stop the timer or not? It's probably not written into the tournament rules. He claims that part of the problem is the real world settings for games - no set of rules can comprehensively cover every eventuality for the kinds of things that real life can bring to a game.
He also examines the concept of 'playing fair'. A very hard concept to define, which he illustrates with a great story about trainers who tried to teach dolphins to play waterpolo: they got the idea of scoring, but when they tried to stop the opponents scoring it descended into all-out war, not just a game.
Two big problems are outlined: working out exactly when a game starts, and when a move really counts. Uses the example of his friendly tennis matches, where it seems there are lots of unstated tweaks to the rules depending on who's playing and what the venue is. The process of learning these nuances is hidden - we don't realise we're learning them - so it's not until someone new tries to join in that the players may realise what they've done/learnt.
Players often adapt and reframe many official rules, depending on circumstances. For example in a friendly tennis match you may not switch ends as often as the rules state, or use new balls so often. Players may also add rules (my example: 6 and out playing cricket at Roedean because of the busy road along the edge of the pitch, his example: chat topics in the different groups he played tennis with).
The author goes on to ask how we can play if we don't know the rules, and suggests that we can play "as if" we know all the rules. This is his difference between human and computer players. Then the chapter veers off into looking at monetary systems and whether we can ever know all of the rules for that etc.
Could be a very useful reference.