*In Part I, game designer Bud Leiser explains how to use the Fibonacci series in system design. In Part II, he shows the grind gap and how the amount of grind can quickly accelerate when using the Fibonacci series.*

So what I’ve done now is shown you the flat progression on the left, so you compare it to the 20% degrade on the right. It makes a huge difference right? But now we need to compare it to sword costs to know what kind of effect it will have on our player grind.

Monster | Reward A | *10 | Reward B | *10 | Difference | Grind Gap |

A | 5 | 50 | 5 | 50 | 0 | |

B | 10 | 100 | 8 | 80 | -20 | -2.5 |

C | 15 | 150 | 10 | 104 | -46 | -4.42308 |

D | 25 | 250 | 15 | 147.2 | -102.8 | -6.9837 |

E | 40 | 400 | 20 | 200.96 | -199.04 | -9.90446 |

F | 65 | 650 | 28 | 278.528 | -371.472 | -13.337 |

G | 105 | 1050 | 38 | 383.5904 | -666.41 | -17.3729 |

H | 170 | 1700 | 53 | 529.6947 | -1170.31 | -22.094 |

I | 275 | 2750 | 73 | 730.6281 | -2019.37 | -27.6388 |

J | 445 | 4450 | 101 | 1008.258 | -3441.74 | -34.1355 |

K | 720 | 7200 | 139 | 1391.109 | -5808.89 | -41.7573 |

L | 1165 | 11650 | 192 | 1919.494 | -9730.51 | -50.6931 |

M | 1885 | 18850 | 265 | 2648.482 | -16201.5 | -61.1728 |

N | 3050 | 30500 | 365 | 3654.381 | -26845.6 | -73.4615 |

O | 4935 | 49350 | 504 | 5042.291 | -44307.7 | -87.8722 |

Ok so let me explain how I did this so it’s not too confusing for some of our readers. On the left we had our flat progression if you remember, so I took that and mulitplied it by 10 to get our weapon cost. In column 5 I did the same thing to our degraded reward system to see how much they would make after killing 10 monsters. Then I found the difference between those numbers to determine the monetary gap. We can see that the player is definitely falling behind monetarily each step and will have to grind more and more for each new level of sword. And finally in the last column I take the amount of money they make from killing monsters to determine how many more monsters they will need to kill at each step to earn the next weapon (in addition to the first 10).

So let’s zoom in on that.

Grind Gap |

0 |

-3 |

-4 |

-7 |

-10 |

-13 |

-17 |

-22 |

-28 |

-34 |

-42 |

-51 |

-61 |

-73 |

-88 |

Here we can see at that level 1, no problem kill 10 monsters get a new sword. YAY! Feels pretty fast for the player, which is good they just started a game we don’t want them to get bored so let’s give them some quick rewards. Now how about level 2? Oh just 3 more monsters that’s not bad right? Then just +4 more, then +7, then +10.

Now let’s pause there for a moment; because I feel it’s important. Remember we started with 10 kills for Sword A. Then we added +3 (13), then +4 (17), then +7 (24). So by the 4th step we now have to kill 24 monsters to get our next sword this is the point where our beginning rate doubles (or another way to think about this is progression rate is 50% of our starting rate). The next step however adds +10 (37) so in a single level we again add 100% compared to our first step! WOW! This is a really really important thing to understand.

Let’s make sure every reader full grasps this curve that we created. In the beginning we leveled our sword up very quickly, just 10 kills. Then it took us 4 steps to double that progression rate. But then in the 5th step it doubles (the base not the current) instantly! This means that each step after this is going to add a huge amount of grind (compared to our first level).

So our progression curve still feels pretty good at this point, it should feel fine and will probably feel fine for a few more levels…. but it could get out of hand quickly. Let’s see what happens next

- +13
- +17
- +22

**200% more grind time**, compared to our very 1st level. And then it gets steep as hell.

*[This article originally appeared on Bud Leiser's personal blog.]*

*Bud Leiser beat Nintendo’s original**Zelda*when he was just 3 years old. Then went on to win money and prizes playing:*D&D Miniatures, Dreamblade, Magic the Gathering*and*The Spoils*. He’s just returned from Vietnam where he helped manage Wulven Studios as their Lead Game Designer. He was responsible for creating internal projects, game design documents and communicating with clients to help them succeed in the post-freemium app market.