The asterisk is to denote that we are referring to an online casino where virtual money is used and that is dwarfed in size by a number of poker-only sites. Still, at roughly 500,000 users a day–the vast majority via Facebook–Seattle’s own DoubleDown Casino is, to all outward appearances, a smashing and largely unheralded success.The idea for the casino, Double Down Interactive co-founder and CEO Greg Enell acknowledges, came out of the success of free online poker. Greg Enell”Why don’t we come out with blackjack and roulette and slots and every other game besides poker and fill that void?” Enell says he and his two co-founders thought. That was less than two years ago. Today, the company, with its 46 employees, offices overlooking Lake Union, and two million Facebook users per month, is perched profitably atop the heap of free online casino games. The secret sauce of DoubleDown is its virtual currency. Every day, a player can expect between $50,000 to $60,000 in free virtual chips–up from $1,000 at its launch in 2009. Maximum bets in Blackjack are $5 million per hand, and in slots up to $1 million per spin. To get into high-dollar games like those, players have the option of buying from 150,000 chips for $3 to spending $99 on 100 million chips. In other words, the site operates on a freemium model, with more than 90 percent of users playing for free, and the remainder putting in actual money. In addition to the obvious advantage of getting to play longer, ponying up real cash enables customers to enjoy an inflated sense of self-worth.”The numbers are big and it’s done that way by design,” says Enell. “We want [paying customers] to feel like they’re rich. We want to give them the VIP experience.”At its inception less than two years ago, Double Down introduced a multiple player blackjack game over Facebook. It followed this with roulette, and then slots, and eventually poker. This week, it unveiled a new tournament slots game, where players compete in flights of 100 to finish in the top 10 to win bonus virtual cash.As we chatted on the phone, Enell acknowledged that his attention was somewhat divided. He was playing in one of his slot tournaments, Jewels of the Dragon, against 99 others. How was it going?”I’m in 32nd place right now,” he said, with a number of spins remaining. “I still have the opportunity to finish in the top 10.”image sourceDouble Down’s “main lobby”Does the company worry about acting as a gateway to real gambling?First off, Enell points out, it’s not as if people are wagering their paychecks on his site. When they lose $5 million on a hand of blackjack, they’ll still have money to pay the Jimmy John’s guy.”There’s a casino on every corner almost now,” he adds. “We are just giving people an online outlet to play games that are widely available to them already.”Double Down does seem to be on to something. In addition to adding users like crazy (players have increased by 25 percent in the past two months alone), the company has been hiring since shortly after its inception. No one yet has quit yet, Enell says (though a few have been shown the door). If you happen to be looking for work, as of yesterday they’re looking to fill 14 open positions , from Java and Flash game developers to a marketing manager.Amidst all these happy numbers, there’s one thing that grates at Enell: The relative lack of media attention his company has received.”Zynga is getting all the press and the buzz about what an incredible company they are… There are 50 articles a day written about them,” he harrumphs, referring to the four-year-old San Francisco-based creator of games like Farmville and Mafia Wars. “One thing we would like to say is we’re right here in Seattle. We’re doing the same thing, on a little bit of a smaller scale. And we’re having the same success.”Assuming people don’t suddenly stop amusing themselves by wagering fake money on Facebook for hours on end each day, Enell’s sought-after attention may not be far off.Follow The Daily Weekly on Facebook and Twitter.