Complexity - or how I build mechanics

 In my last post I brought up my concept of Complexity as a measurable metric in TTRPGs, but haven't really explained how to use it or how I came up with it - so here goes: Complexity and its steps - the Lego bricks of TTRPG mechanics.

What is Complexity?

To reiterate my definition of Complexity as a metric: It is the number of elementary steps a plyer needs to perform to resolve an in-game mechanic.

This "number of steps" seems kind of vague, so how do we measure them? A good rule of thumb is that whenever you try to describe the mechanic in simplest possible way and find yourself using a comma, period or the words "and" and "then", that's probably the boundary between individual steps. To use a new example, let's break down a Skill check in the Year Zero Engine games:

"... start by adding the skill value and the attribute value together. The sum determines how many six-sided dice you need to roll. Rolling a six counts as a success." - Vaesen, by Free League

I highlighted the breaks between individual steps with bold - in this case only periods. Observant reader will notice that the word "and" is not highlighted - that is because it if we took the sentence apart at that point, the individual parts would not make any sense.

So now if we try to simplify the language, the steps of a Skill check can be summarized as:

1. Add skill value to attribute value
2. Roll that many dice
3. Find all 6s

This puts us at Complexity 3 for average YZE skill check.

Not all Complexities are created equal

"Regarding the Complexity of operations, it's generally accepted that their order of complexity is:
comparison, addition, doubling, multiplication ~= subtraction ~= halving, division, and beyond that the more complicated operations."

As a comment on my last post (quoted above) rightfully pointed out, some operations are simpler to perform for an average human - which can be an issue if we're using Complexity to assess the mental load of a mechanic. The nomenclature doesn't exactly match mine, as whether you add or subtract, it is still only one step you need to perform, but the point that some actions are easier to process is absolutely right. If we had two mechanics, both at Complexity 3, but one involved comparison and the other division, there would be a noticeable difference in their mental load.

So how do we solve this problem? In my opinion, simply by being aware of it, as Complexity is not an "end all be all" metric to accurately assess the mental load of a mechanic. I would say that a task of Complexity of 4 will always be more mentally demanding than a task of Complexity 3, even if the former's individual steps were far easier to process. Much like Lego bricks, some are easier to connect and work with than others, but building something out of 10 bricks probably takes less than to build something out of 15.

To accurately assess the mental effort a mechanic demands, we'd probably need a new concept - like "Effort" - which would assign values to the individual steps and their number.

So, what is Complexity actually useful for?

Short answer: Quickly differentiating mechanics based on how much they take (time or mental effort).

Long answer: As I alluded in the previous paragraph, because mechanics with the same complexity have different individual steps, they also better serve different purposes - that's why I liken it to Lego. Based on what bricks you used, you can end up with drastically different sets. And more impressive sets generally tend to have more bricks and are assembled out of more individual sections, rather than built all at once. 

Complexity is only a tool for assessing your mechanics. It can help you quickly and relatively easily (and these are its main strengths as a metric) assess how much your project demands of its audience on average, help you clearly see which parts of its gameplay are more emphasized than others, and to compare competing ideas based on how much engagement (and accompanying mental load) you want at certain points.

Higher/lower Complexities are not universally better/worse. If you're looking for a core mechanic, lower score might seem better - because you don't want your players to mentally burn out over mundane and routine tasks, before they can get to the "larger, more impressive sections built out of more parts". However if you choose a slightly more complex core mechanic, but can utilize it throughout the whole game without needing to pack on many more steps (keeping the Complexity roughly constant), you can ensure everything stays "balanced", all parts of the gameplay feel almost equally as important and as if they carry actual weight - whereas lower Complexities lend themselves better to things that players are barely even aware they need to do, and can thus remain more immersed in the fiction part, rather than the "game" part.

Likewise, if you want to emphasize some part of the game to feel like it takes time and is more demanding, higher Complexity can better simulate that experience because the players will themselves feel like the procedure takes time and effort, so the immersion will be more natural, rather than acted out. After all, the main objective of any mechanic is to simulate a certain feeling/experience in the players.

Conclusion

I originally came up with Complexity as a metric roughly a year ago, when I needed to quickly assess competing ideas for a core mechanic, which ones to playtest first, or whether they would even be compatible with rest of the game. Since then, I have refined the idea somewhat, and found it a useful tool whenever I am coming up with something new. Do I want this to feel quick and easy - barely requiring the player to refocus from the in-game events, or do I want more mechanical rigor and more methodical approach? How does it compare to other mechanics within the same section of the game? Am I demanding too much for anyone to want to engage with it or would playing it feel rushed and unsatisfying?

While Complexity never answers these questions fully, it's been a useful tool for me to compare ideas for both the whole game, and individual sessions.

Thanks for reading, enjoy your next game!