What is "Substitutable Good"?

In game design, a substitutable good is a game element or feature that can be replaced or exchanged with another without significantly altering the overall player experience or the intended design outcome. This concept is rooted in the idea that certain game elements possess interchangeable characteristics, allowing designers flexibility in their implementation while maintaining the desired impact on player engagement, enjoyment, or progression.

A classic example of substitutable goods in game design can be seen in the customization of character appearances. In many games, players can choose from a variety of outfits, hairstyles, or cosmetic items to personalize their characters. These items are often substitutable goods because, while they may vary widely in aesthetic appeal, they don't fundamentally alter the core gameplay mechanics or narrative structure.

Changing the price of a substitutable good even slightly may change its appeal in the eyes of players. Where there are many items of similar power levels to choose from, players may opt to choose whichever is the cheapest. Thus, if one such item's price is made slightly more expensive than similar items, players may stop buying it altogether. The opposite may be true if it is made cheaper than similar items. This also explains why items on sale may become dramatically more lucrative than any alternative item.