in game mechanics, these are called a variable rewards (also, yay)

Variable rewards are game mechanics that provide unpredictable or randomized incentives to players, designed to encourage repeated engagement through the uncertainty of outcomes. This concept is commonly used in video games and gamification systems to create compelling feedback loops that maintain player interest. The mechanics leverage psychological principles of reinforcement to drive continued participation and behavioral patterns.

Source: Yohei Nakajima (X) | 2026-07-07