The Rules We Forget

In almost ever game we play, there are rules we "forget".  These rules are the extra rules that no one uses, the rules we ignore for the sake of fun.  In roleplaying games, the GM / DM is essentially defined by the rules he or she doesn't use.  So what are these rules and why do we keep including them?

Rules are written like walls for the game.  They separate the agreed upon model of whatever the game is about, from the things that conflict or break the model.  If you don't put in encumbrance rules, you end up with players carrying around 100 sets of full plate armor in their backpack.  If you don't put in rules for the details of how many words a player can say during their turn, the game doesn't resemble reality anymore.

For the game in play though, rules are like lines on the road: they only mean something if everybody follows them. The DM, despite his apparent position of power, can't monitor every rule every time.  He isn't the police officer, responsible for enforcement.  He is the driving instructor, teaching people the importance of the rules and following them.  If he doesn't care about encumbrance, no one else will.  If no one is breaking the game with encumbrance, it doesn't matter anyway, right?

So why is there this gap between the rules as written (RAW) and rules as played?  The bottom line is that not all rules are created equal.  Some rules are what the game is about.  Some rules are about having a consistent game model.  Game model rules are the rules you don't need, until you do.  They are the rules that form the fences to keep min-maxers and OP PCs out of trouble.  They aren't the rules you need everyday.  And if you gaming group is reasonable, you never need them.

The model rules are also the models used to equalize the level of detail across the simulation of whatever you are simulating.  For example, maybe you really want to have flanking in your new awesome game system.  You feel however, that if you have flanking, you have to include facing so you can't flank two targets in opposite directions.  But, if you want to include facing, you now need a rule on how to change facing.  No one really may want a rule for changing facing, but the model may not make sense, unless you include it.  However, now that you have facing, now you need a rule that describes who you can attack based on your facing.  If you game really cares about individual moves of the sword, maybe you even need to know which targets you can attack with the weapon held in an individual hand based on facing.  All of this is driven by the level of detail of the model.  In the end, hopefully the level of detail matches the level of what the players care about.  If not, start over with different assumptions and iterate.  This very much resembles the evolution of gaming systems over time.

This model detail problem is one of the reasons that rules-light system become so popular.  Rules-light systems don't include a lot of detail, and thus, don't include specific rules for everything.  Instead, they focus on capturing the important things with the minimal level of detail required.  They focus on what the players really care about.  The great thing is that GMs can apply this exact principle after the fast to customize their game.  This is another reason we leave out rules.

Game writers will get judged on how elegant, complete, and concise their rules are, GMs will get judged on how fun and empowering their games are, and players will still just keep looking for a good time.  In the end, all of these jobs are important for that end player goal, even though not all of the rules are needed.  Throw out the ones you don't need in your group, and drive on with having fun.