I’ve been reading a collection of philosophical essays, titled “Tieto, totuus ja todellisuus”, for some months now (slowly but with certainty. A particular article by Jaakko Hintikka contained a bit of terminology I found useful. It is related to games.
In game theory, rules are what define a game. They tell what one can do within the bounds of the game.
For example, in chess: Turns, moving different pieces, winning, stalemate.
The interesting part was strategic rules, which essentially tell what moves one should make in order to win (winning, in game theory, means maximising utility, and utility functions are something beyond the scope of rules; see, for example, playing against/with young kids, where you are likely to have different goals than you have in normal play). E.g. in chess, you generally don’t want your queen to be eaten.
As a contrast to (most) roleplaying games, take a competitive game that has a winner. Assuming it is a good game, players will be making (strategic) choices, which will to some extent determine who wins the game. In my experience, it usually takes a bit of play to really understand these games, which is the same thing as learning some strategic rules. Simply playing the game may be sufficient, but maybe being taught by someone or reading books is more convenient or efficient. Be that as it may, once certain level of competency is achieved, then the intricate and interesting parts of the gameplay open.
Sometimes the learning process outlined above is interesting in and of itself, someties a nuisance. Personally, I only find gameplay meaningful after understanding what the game is about, in a sense.
This is far less true of roleplaying games (again in my experience); most of them are fundamentally the same game with different defined rules. There are two major exceptions: Intricate subsystems (combat and character creation are the most common) and the more divergent Forgey games.
The lesson here is that mechanical rules, in and of themselves, do not matter a whole lot. Maybe I roll 2d6 and add skill, or maybe I compare an attribute to value indicated by a table. The difference is minor, unless the way the game is played changes significantly. For example: If the way to solve problems is to have a character with suitable skill or spell, then the art of character building is important, but if the way the player approaches the problem is what determines the success of a given action, then wits and reading the GM’s/game desiger’s mind are more important, and the actual character played matters less.
Forge wisdom sayeth: System matters. The best way to investigate this claim is to play different systems and see if there is a difference. Here’s my refinement of the phrase above:
Take two games. Between these two, system matters to the extent that a different set of strategic rules is necessary for enjoying the different games.
The above has little to do with system as defined in Forge glossary (as it encompasses defining and strategic rules actually used in play) and even less to do with the content of the system does matter essay, which is focused on GNS and so on.