Randomness in game design

http://playthisthing.com/randomness-blight-or-bane

When Chance isn't Random: Regression to the Mean

In reality, the reliance by games on chance does not necessarily mean that the game's final outcome is random. In a game with chance elements, there will typically be dozens or hundreds of random tests over the course of the game -- many, many times in which dice rolled, or an algorithm that uses a random number as an input applied.

Paradoxically, the greater the number of random tests, the less effect chance has on the outcome. Over time, random systems regress to the mean.

Consider a single die-roll: there is exactly a 1/6th chance of each possible result. Now consider a 2D6 roll (that is, rolling two six sided dice and summing the numbers rolled): There is a 1/6th chance of rolling a 7, but only a 1/36th chance of rolling a 2 or 12. A single die-roll produces a flat curve, with all outcomes equally probable; a 2D6 roll produces a bell curve, with numbers toward the center of the curve more probable, and the extremes less likely. Adding more dice increases the sharpness of the curve.


http://playthisthing.com/randomness-blight-or-bane