Some of the most hardcore gamers appreciate Uno. With commands like Skip, Draw Two, Draw Four, and Reverse, it can get pretty cutthroat for a family-friendly card game—and that's despite the fact that most people aren't even playing by the official rules.

In 1971, a barber and devoted card player named Merle Robbins developed the game based loosely on the rules for Crazy Eights. He played it with friends and family, who enjoyed it so much that Robbins wondered if he could market it outside of his social circle.

The rest of the Robbins family (including his wife, Marie, his son Ray, and his daughter-in-law Kathy) agreed that he was on to something. They saved up $8000 to pay for the first printing of the game, just 5000 copies to be sold at the barber shop and the local Kiwanis Club. Robbins’ instinct was right—it was a hit, and word-of-mouth spread quickly.

By 1972, Robbins was reportedly able to sell the rights to funeral parlor owner Robert Tezak from Joliet, Illinois, for $50,000 and a 10-cent-per-deck royalty. Tezak was such a firm believer in the product that he founded International Games, Inc., just to market Uno.

At first, International Games looked like it would have to fold. Distributors weren’t interested, and toy stores didn’t want to stock it. But word-of-mouth was still going strong: Over a span of three or four years, nearly 40,000 people wrote the company to ask where they could find a copy of the new card game craze they had heard about.

And in 1978, International Games got their big break: K-Mart agreed to put Uno in their stores on a national level. Sales skyrocketed—more than 100 million Uno games have been sold since it was invented in 1971, thanks in part to Mattel’s purchase of International Games in 1992.

But despite the game's popularity, most of us aren't exactly playing it the way that the creator intended. Chances are, you follow these rules: Discard the cards in your hand by matching colors or numbers, and follow the instructions on the special cards. The first player to discard their whole hand wins. Right? Wrong. According to Mattel [PDF], “The first player to play all of the cards in their hand in each round scores points for the cards their opponents are left holding. The first player to score 500 points wins the game.”

And there’s more:

Stacy Conradt

We don’t know about you, but we're going to declare House Rules and ignore this whole points business.