Last Christmas, I tore the wrapping paper off a rectangular box, expecting at best I'd see an iPad, at worst a Kindle. Instead, I was staring down at a board game: Settlers of Catan. In an era of Xboxes and Wiis, my gift ranked just above a framed photo of the gift-giver and just below nose hair clippers.

But multiple marathon gaming sessions later, Settlers of Catan stole my heart.

I'm not the only one. Over the past few years, Settlers of Catan has transformed from an activity enjoyed by a small niche of gamers into a mainstream hit. With sales nearing 25 million copies worldwide, Settlers of Catan is becoming the most popular board game since Risk and Monopoly.

After Settlers was first released in 1995, a small but passionate following emerged. It wasn't until a decade later that the game's popularity began to blossom. "The start of the tipping point was 2008," said Bob Carty, a spokesman for Settlers manufacturer Mayfair Games. "Settlers is three to five years away from being a household word." Last year alone, the game's sales grew 35 percent. Carty said that the game is mainly played by families, but it's also popular on college campuses and as a team-bonding activity at companies.

Part of Settlers' success can be attributed to its well-designed gameplay. Adam Weisberg, a finalist in the 2006 Settlers of Catan US Championship, notes that the game "is easy to learn because it draws on equal parts strategy, gamesmanship and luck." The rules give you enough choices to keep it interesting, without so many as to make it overwhelming. As a result, says Weisberg, "with a little luck, a sharp new player always has a chance to beat an expert."

Invented by German designer Klaus Teuber in the mid-1990s, Settlers of Catan involves three or four players building settlements, trading resources, and racing to earn 10 victory points. Each game begins with a shuffling of the board tiles, producing a wholly different board each time. Settlers allows players to produce resources, build roads and settlements, buy "development cards," and trade with one another.

Where games like Monopoly fall short—with playing times that far outlast the players' interest, particularly those who have little hope of victory—Settlers is designed to maintain close competition. Unlike games of Risk that can famously last for days, Settlers usually takes 90 minutes or less. And unlike many pastimes that quickly descend into cutthroat competitiveness, Settlers of Catan is not a zero-sum game. A single roll generally produces resources for multiple players, and trades are almost always mutually beneficial. Because Settlers is a unique game that rewards cooperation as much (if not more) as confrontation, Weisberg argues that it "brings out competitive spirits in a positive way."

Still, plenty of well-designed games remain mired in obscurity. There are a number of theories explaining how Settlers expanded out of the geek basement to corporate breakrooms and household living rooms. Blake Eskin argued in the Washington Post, for instance, that Settlers has taken hold because it exemplifies many aspects of our modern world, such as limited resources and intertwined global economies.

Another way to view the mainstreaming of Settlers is part of the larger trend of "nerd culture" slowly infusing into "popular culture." For example, while X-Men and Green Lantern were once idolized by just a sliver of society, now millions go watch them at movie theaters in a seemingly endless parade of superhero movies.

Settlers is taking a similar path to popularity. Not long after its inception 16 years ago, Settlers found a welcome home among gamers. "The nerds recognized it first" argues Charlie Cromer, a nerd culture enthusiast who's been attending gaming conventions for the past decade. "They were the ones willing to take a chance on an obscure foreign board game." In the case of Settlers, nerds were the early adopters that Malcolm Gladwell discussed in his book The Tipping Point, a necessary component for a product to take off.

But the game isn't too nerdy for mainstream players. Cromer, a Settlers aficionado, sees its mass-culture appeal stemming from the game's "lack of strong setting or theme." In other words, "if it was in a strongly fantasy-based setting, or any genre-specific world, it wouldn't have broken through." Settlers' palatability is its salvation.

Settlers' recipe for success can therefore be seen as this: a well-designed game, devoid of a geeky patina, incubated by early adoption into a nerd culture that has become increasingly mainstream.

Though Carty predicts Settlers is still a few years away from being a household name, it's already showing signs of entering our popular consciousness. As I was writing this post, WalMart.com was completely sold out of the game. As of this week, two different versions of Settlers were in the top 10 board game sellers on Amazon—and neither Risk nor Monopoly were in the top 10.

Increased popularity of the game at home has resulted in higher tournament popularity as well. Five years ago, there were 100 entrants in the Settlers of Catan US Championship. This year, there are 10 to 15 times that number, spread across 32 qualifying events. Next year, that number is expected to double to 64 events, according to Carty.

Name-dropping Settlers at random may still leave you with blank faces today. But in the near future, a once-obscure German board game will likely be seen as American as apple pie.

For a rebuttal to this article, see "Sorry, Settlers of Catan Is Not the New Monopoly."

Two decades after it was invented, this game is about to become a household name. How did it happen?