The 80/20 rule, also known as The Pareto Principle, states that for many situations, 80 percent of the effect comes from 20 percent of the causes. This idea is most commonly used in economics, and in fact originated from Italian economist Vilfredo Pareto's observation that 80 percent of the land in Italy was controlled by 20 percent of the population. It is claimed that he later developed this into a principle when he noticed that 20 percent of the pea pods in his garden accounted for 80 percent of the peas.
A 1992 United Nations Development Report found that the richest 20 percent of the world population held 82.7 percent of the total income.
The principle can apply to many aspects of business, such as 80 percent of the sales come from 20 percent of the profit, or 80 percent of the profits come from 20 percent of the time spent open.
This principle can also be easily applied to games. The idea is that 80 percent of the time spent playing, the player will be experiencing just 20 percent of the content. There may be plenty of features in a given game, but the player will not be experiencing everything at once. For example, in a typical Mario game, there are a large number of enemies and levels. Players can only be on one level at a time, however, and will generally only face a few enemies at once. The features found in the Core Gameplay Loop will hold the vast majority of the player's time. This would be mechanics of jumping, the most common enemies, and the process of moving from left to the right through the levels. Developers should be sure focus intensely on that 20 percent of content which is most used. Treat it as a much higher priority than the rest of the 80 percent, or the overall game will suffer.
Acosta, Keyvan, et al. "The 80/20 Rule" 100
Principles of Game Design. Ed. Wendy Despain. Illus. Raymond Yuen. San
Francisco: New Riders, 2013. 64-65. Print.
United Nations Development Programme. Human Development Report 1992. New York:
Oxford UP, 1992. Print.