Cow Clicker is a Facebook game about Facebook games. It's partly a satire, and partly a playable theory of today's social games, and partly an earnest example of that genre.
You get a cow. You can click on it. In six hours, you can click it again. Clicking earns you clicks. You can buy custom "premium" cows through micropayments (the Cow Clicker currency is called "mooney"), and you can buy your way out of the time delay by spending it. You can publish feed stories about clicking your cow, and you can click friends' cow clicks in their feed stories. Cow Clicker is Facebook games distilled to their essence.
The game can speak for itself, and some players might want to let it do just that. Others may be interested in my extended thoughts on the work and why I made it. You can read those here.
In January 2011, six months after the release of the original, I launched an expansion to Cow Clicker, extending its satire from social games to gamification, platforms, and app stores. Now you can cowclickify your website or app with Cow Clicker Connect or the Cow Clicker API.
Screenshots (click for larger versions)