The Curse of Cow Clicker: How a Cheeky Satire Became a Videogame Hit
archive.wired.com/magazine/2011/12/ff_cowclicker/all
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Ian Bogost created Cow Clicker as a critique of Facebook games. Taking his cue from FarmVille, which encourages players to personalize their homestead with special crops and equipment, he drew a series of cows for his players to buy with virtual mooney or real money. As the game grew more popular, Bogost found himself cranking out dozens of new cow designs to keep his players entertained.