Formal Method

Description
Formal Method is the name given to a set of techniques used in game design taken from game theory, statistical analysis, and probability analysis. The methods are used to determine game balance, player strategies, player choices, and game mechanics. 

Methods
(Links)

Plundering the Seas of Probability Statistically Speaking, It's Probably a Good Game, Part 1:Probability for Game Designers Applying Risk Analysis To Play-Balance RPGs Formal Models and Game Design Techniques for Achieving Play Balance Game Theory Applied To Game Design Applying Game Theory to Video Game Design

(Literature)
Game Architecture and Design: Learn the Best Practices for Game Design and Programming
Fundamentals of Game Design (2nd Edition)
Introduction to Game Development, Second Edition