Game designers all know that you should edit until you have a game that works as you intend and until the instructions are clear. But most game designers stop there. I suggest you also edit until your rules are easy to remember.
I would argue that for most games, your players should not have to look at the game text after the first five minutes of the game. You should write rules so that players don't need to constantly look through the book.
Sure, there are games that are exceptions to this. Some players revel in referencing 500-page tomes during play. But since most of my audience are story gamers and free form players, I challenge you to structure your rules so they are memorable enough that your book is rarely needed in play.
How can we do that? It turns out that there has been a lot of research in the field of education on how to teach people in a way they can remember. Here are six tips for making your content more memorable:
People remember the text at the beginning of a section better than anywhere else. The most important rules should be placed here. The things that players need to use the most often should also be here.
EmotionWhen you have strong feelings about a subject, your memory about that subject also tends to be stronger. One way to use this is to include examples of play where players are having fun playing your game or who are frustrated that they are confused. Give the reader someone to empathize with, and they will be able to remember the rules better.
Your brain tends to notice anything that is new or strange. If you have an important rule buried in the middle of less important stuff, figure out a new or strange way to highlight it visually. You need to give the reader clues about any new information that you want them to focus on.
If the connection between sections makes sense, or if the sections relate to things that the reader already know, the memory is stronger. The easier it is for the reader to see connections, the deeper the memory tends to be. Make sure the sections of your game text are arranged in a way that makes sense to the reader.
Facts out of context are difficult to remember, but if the reader has a reason to care about a subject, it is much easier to remember. In other words, if we know why we should remember something and we agree that it is important, it is much easier to remember. Whenever you have given your reader a complicated rule or a long section of text, make sure you include an explanation as to why this text is important. Why have you included ten pages of grappling rules? Why should the reader care?
People remember the text at the very end of a section almost as well as they remember the beginning. The second-most important information should go here.
Bonus Tip: Break It Up!
Because people remember beginnings and endings so well, you can sometimes trick people into remembering more by breaking up large sections into smaller sub-sections. Breaking things up creates more beginnings and endings. This doesn't sound like it would work, but it does.