(CNN) -- What's so addictive about a Scrabble-like online game that it can get you kicked off an airplane?
Non-gamers have been asking that question since actor Alec Baldwin was booted from an American Airlines flight Tuesday in Los Angeles for refusing to turn off his phone. His reason? The "30 Rock" star was in the middle of playing "Words with Friends."
For the uninitiated, "Words with Friends" is a multiplayer word game that people play online, usually on their phones or via Facebook. Like Scrabble, players receive a random assortment of letters on tiles and must use them to form words on a crossword puzzle-like grid. Words with rare letters such as Q or Z are worth more points.
Players take turns forming words, with their phones pinging them when it's their turn. Games can go on for days or even weeks, and some WWF addicts simultaneously juggle multiple games against friends or random opponents.
"I'm down to about seven games at the moment, but I've been up to 20 games at one time before," said Matt McCalley, 24, of Charleston, South Carolina. Before his buddy Keith beat him last week, McCalley said he hadn't lost a game since last summer.
"I'm very competitive," he said. "I just really hate losing."
"Words with Friends" has 12.5 million active monthly users, according to tracking service AppData. Baldwin isn't the only celebrity who plays it -- John Mayer, Lindsay Lohan, Michael Phelps and Ludacris are also fans. Humor site Cracked.com has called it "the crystal meth of language games."
Sarah and Jonathan Elmer play the game on their iPad nearly every night before bed. The Kennesaw, Georgia, couple team up to play against their friends and usually have several games going at once.
"It's super fun," said Sarah Elmer in an interview. "It's not like 'Angry Birds,' where there's no point to it. You're actually educating yourself while you're playing."
She also likes the ease and portability of playing the game on mobile devices.
"It's replaced the whole carrying-around-the-newspaper, crossword puzzle thing."
The Alec Baldwin airplane episode has brought renewed attention to the game, which has been one of the most downloaded apps in Apple's online store since it debuted in 2009. In an e-mail to CNN Tuesday, Baldwin spokesman Matthew Hiltzik said, "He loves WWF so much that he was willing to leave a plane for it ..."
Baldwin himself mentioned the game in his tweets Tuesday before mysteriously deactivating his Twitter account.
For Zynga, the game's maker, the news has been a marketer's dream. The company started a Twitter campaign, #letAlecPlay, and released an "official statement" -- a "Words with Friends" game board spelling out the same message, along with a scoreboard showing "A Baldwin" 1, "American Air" 0.
Some bloggers have noted wryly that the whole episode is a publicity coup for Zynga before the company goes public later this month. The flap also seems to have energized the WWF community, many of whom have been trying to invite Baldwin to play the game with them.
"I'm not about to get kicked off a plane [for playing the game]. If they wanted us to turn off our phones, I would," said "Words" fan McCalley. "But I have respect for that kind of commitment."