"Add things until it starts sucking, take things away until it stops getting better."Good systems find a balance between keeping the player guessing and keeping things simple; this means both knowing how many options to provide the player, and knowing when to say no to something regardless of how cool. It involves things like how many weapons to have in the game, how many talent trees, or how many monsters to spawn in an encounter.
1, 1, 2, 3, 5, 8, 13, …
There are two applications of this sequence that I apply to game design: the Rule of Three (extended edition), and the Golden Ratio.Link: The Short form to solve for the Golden Ratio
The Golden Ratio, like the rule of three, crops up all over the place.Link: Vitruvian Man compared against golden ratios
From the very small to the very large it shows up, and there is something about it that we find pleasing. Where am I going with this? Anyone that has done this already knows where I'm headed, so let's catch you up.Reward = Coefficient * (GoldenRatio ^ (Level + Exponent))
Things usually deviate from this, especially when systems start interacting, but it's usually a nice starting point with pleasing results. OK, you say, what about a real world example of how to use all this Fibonacci game design? Let's take a look at MK9.Link: A Screenshot Of The File I Used
As an aside, I was also tracking the kind of gameplay gimmicks being used, how many times different characters occurred, what arenas it took place in, what kind of ring knockouts used, etc. Missions were constantly being shuffled around, and keeping this file maintained was a full time and commitment heavy job, but it was so worth it.Reward = 50 * (2 ^ Difficulty)
This gave me nice round numbers that started off at 100. The final outcome looks random, but you can see that at every step of the process I was making meaningful calls about how things were organized, and, more importantly, you probably noticed the constant appearance of 2, 3, and 5 in the design. That was all on purpose."When forced to work within a strict framework the imagination is taxed to its utmost — and will produce its richest ideas. Given total freedom the work is likely to sprawl." – T.S. EliotDesigns with no structure tend to sprawl. It's something that we all understand, but it can be very hard to follow that advice. Being a designer means you have the heart of a dreamer, or you wouldn't be doing the job in the first place. We like adding shit, because we traffic in a world of cool. Isn't it better if we add more? Probably not.
Todd Boyd 
A wonderful article, Mike... thanks for writing this! I've already applied several of your guidance tips to my current project, and this one will seriously help me get my XP rewards, level caps, and such in check.
I've always loved to program, and I've always loved games... but the system design of it all is still fairly new to me. 


Joe McIntosh 
Nice story, thanks for sharing!



Maria Sifnioti 
What a great article. I really liked your design approach. Thanks!



Kevin Bray 
This is an interesting theory, though I have to point something out... 1, 2, 3, 5 aren't only Fibonacci numbers, they're also prime numbers. Just because these numbers are useful for game design and they happen to be the first few Fibonacci numbers does not mean that all Fibonacci numbers are all useful. For instance, the next Fibonacci number is 8. 8 is not a terribly useful number, simply because it can be factored as 2 * 4, or 2 * 2 * 2... none of these numbers besides 2 are particularly useful for balancing. That being said, it seems to me that the real trick here is odd prime numbers. Once you have an odd prime number (any prime number greater than two), then you end up with a "balanceable" situation  you can now have unbalanced relationships between individual elements. However, you should keep in mind that this relationship means that you have (SUM 0,n1) number of interactions that need to be considered. For example, if you have 3 character classes, then you have 2 + 1 interactions (in this case, 3). If you have 5 character classes, then you have 4 + 3 + 2 + 1 (10 interactions). If you have 7 character classes, then you have 6 + 5 + 4 + 3 + 2 + 1 (21 interactions). If you have 11 character classes, then you have 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 (55 interactions). And so on.
To sum up:  I believe the reason why you need an odd number is so that each mechanic has an even number of competing mechanics to interact with (simplifies balancing).  I believe the reason why you need a prime number is so that each mechanic is "unique"  if it's not prime, you can simply divide up your mechanics by some factorization. In short, a "prime" number in this context is the simplest possible breakdown of your game's mechanics (or at least it should be). It cannot be broken down (factorized) further. 




Raymond Grier 
There seems to be an attempt here to treat numbers as special. Whether or not they are Fibonaccian or prime is irrelevant. They are small numbers so they are often easier and more convenient to apply to design. The important thing is to make decissions based on reasons you can give a logical reason for
ex: give Link 3 kinds of armor to choose from because he will change armor less often than if he is given 20 to hold onto simultaneously. 


Kain Shin 
Fascinating... I have always been a life disciple of 3 and the Golden Ratio, but I never attributed those to a common denominator. Thank you. I'm going to run with this idea outside of work, too.



Romain Aymard 
Nice post, thanks a lot !



Rafael Posnik 
Awesome article man, very impressivel!



Jeremie Sinic 
Yeah, great read. I am not a game designer but I liked it.


