The Zynga Abyss

Benjamin Jackson, in an excerpt from one of the first Distance essays:

The primary characteristic of unethical games is that they are manipulative, misleading, or both. From a user-experience standpoint, these games display dark patterns, which I define as common design decisions that trick users into doing something against their will. Dark patterns are usually employed to maximize some metric of success, such as email signups, checkouts, or upgrades; they generally test well when they're released to users.

For example, FarmVille, Tap Fish, and Club Penguin play on deep-rooted psychological impulses to make money from their audiences. They take advantage of gamers' completion urge by prominently displaying progress bars that encourage leveling up. They randomly time rewards, much like slot machines time payouts to keep players coming back, even when their net gain is negative. And they spread virally by compelling players to constantly post requests to their friends' walls.