Hooked: How to Build Habit-Forming Products

by Nir Eyal

This is in contrast with companies making products exhibiting infinite variability—experiences that maintain user interest by sustaining variability with use. For example, games played to completion offer finite variability, while those played with other people have higher degrees of infinite variability because the players themselves alter the gameplay throughout. World of Warcraft, the world’s most popular massively multiplayer online role-playing game, still captures the attention of more than 10 million active users eight years after its release.31 FarmVille is played mostly in solitude, but World of Warcraft is frequently played with teams; it is the hard-to-predict behavior of other people that keeps the game interesting.