Cohesion and Symmetry
What do I mean by cohesion? It’s simple. It’s about symmetry in the mechanics. I personally think that having too much stuff taking up players’ Random Access Memory is bad. Thus, I work to make my games to work in a somewhat symmetric way, where the mechanics reflect each other and use similar logic.
This is also why I abhor using ‘floating numbers’, numbers used only in one calculation, just to balance the game’s numbers out to either seem realistic or be balanced in general. Every floating number is more RAM taken from your players, and when the players inevitably forget it at some point, the calculation cannot be done without the floating number, resulting in searching for the calculation from the rulebook. This is why symmetry is so important. By having symmetry, where all related things are filtered the same way, even if they use a floating number, the logic within the players’ head doesn’t stop.
For the same reasons that I use symmetry, I also prefer the use of abstractions due to this. When you need to attest to realism and believability with accurate numbers, you are often limiting yourself to working with floating numbers to balance the numbers out. However, if you simply abstract these things, you can avoid the problem entirely.
For example, let’s look at a situation. There is a ravine the player must cross. It is wider than you could easily jump over.
In a game without abstraction: The ravine is 15 feet across. Your jumping distance is equal to your strength in feet. Your strength is 13, so you need to make a check with some Target Number to succeed.
In a game with abstraction: The ravine is wide. Make a check of some Target Number to succeed.
Abstraction removes so many unnecessary parts of the equation. How is the game enriched by knowing the exact width of the ravine? How is it enriched by knowing how far the character can physically jump? If any of these things were important, then you can simply look at the Target Number and reverse-engineer the distance, hell, the game can even provide the Target Numbers for different distances. These extra steps were completely unnecessary.
But what about jumping distance giving automatic success when it’s within its range? Well, you can do it when it’s abstracted, too. People just assume that you need strict numbers to do that. Just tie whatever you use to jumping into a Target Number that it can automatically succeed. Hell, use it for other features, too.
One of the best ways to make a cohesive game is to have layered mechanics. This is when instead of changing the functionality of the game itself entirely, you signify the change within the game with another mechanic layer on top of the previous one. This keeps the previous mechanics still intact, but just adds something more to the play during it.
The easiest way to explain this is with an example of a combat mechanic. Instead of changing the entire ruleset and dividing everything into limited actions you can take (which basically turns the game into something else), you can layer the mechanics on top of the existing game. So you have a turn order and a limit on the amount of actions you can do. However, you interact with the world with the same mechanical systems as you did previously, so you have a skill for using a weapon and simply use that exactly how you would use a skill for lockpicking, for example.
This reduces the clutter you have in your game, and makes taking actions within the game clearer, because the connection to the mechanic has been made, and is only strengthened when it works exactly how it did before.
Game’s written length is often an indicator of many things, and due to common ways of creating games, it is often an indicator of cohesion, too. Or lack of it. The more subsystems a game has, often the less general cohesion it has. This comes back to simple mathematics, the more factors there are, the harder it is to keep it all together. Some games have succeeded beautifully in creating games with a lot of cohesion while having a long rulebook, but they are the exception.
Short games aren’t automatically more cohesive, though. You can make a very incohesive game in a short package, but usually a shorter game will focus its factors to one or two points, making the entirety more cohesive.