PLAINVILLE — With just a few clicks or swipes, a digital slot machine pops onto the screen, bringing all its clamorous, garish allure as it simulates a jackpot win.
It’s almost as if you’re at the casino, instead of playing online on your phone or laptop, and that’s pretty much the point. Think of it as a dry run — designed to lure more customers to Plainridge Park Casino to play for real money.
The online game, which Plainridge recently unveiled, is troubling to critics of problem gambling. The game has a major difference with the slot machines: Players who spin the wheels on the online game are far more likely to win — and win big — than they will if they go to the slots parlor and wager real money.
That could give players a false sense of confidence when they play at the casino, where slot machines are programmed to take in more than they pay out, gambling specialists say.
“If the games look the same and sound the same, but the payback of one is much lower, then that’s misleading,” said Natasha Dow Schull, an associate professor at New York University and the author of “Addiction By Design: Machine Gambling in Las Vegas.” “The question is whether this kind of marketing, while fine for shoes and other consumer items, is acceptable for gambling.”
Schull said online casino sites have a bait-and-switch quality to them because their large payoffs condition players to expect the same at the casino.
The goal of online slot machines, a growing trend known in the casino industry as social gaming, is to “prime your system for gambling — to hook you in,” she said.
The games are purely for fun, with no chance to win or lose money. Players can win credits, which mimic the thrill of a cash win and unlock new levels of the game, but cannot redeem them at the Plainville casino.
Instead, the games are designed to introduce players to the excitement of gambling and whet their appetites for the chance — however slim — at real winnings.
“It’s marketing and advertising to get people to come to your casinos,” said Jason Elison, who works for a Las Vegas-based game testing laboratory that state regulators, including the Massachusetts Gaming Commission, use to ensure that slot machines are compliant.
Eric Schippers, senior vice president for public affairs for Penn National, the company that owns Plainridge, acknowledged that players have far better odds of coming out ahead online, but said the frequency of wins is comparable.
“As a percentage of spins, the winning experience online is similar to the one at the casino,” Schippers said.
But the jackpots are far higher, creating the illusion of success. Because the credits have no real value, casinos are happy to give them away in bulk. Atop the weekly leaderboard was a player who had amassed 11 trillion credits, and the all-time winner had raked in more than a quadrillion.
The site also seems designed to expand Plainridge’s customer base. A prominently displayed button allows players to e-mail friends the message: “I’ve been playing slots for free on HollywoodCasino.com. I think you would like it. Come and join me and get free 50,000 credits!”
Sending the message also earns 100,000 credits.
The state Gaming Commission, which regulates the Plainridge casino, said it has no authority over its online arm, and said such games are widespread.
“It is becoming increasingly commonplace for casino companies (and many other companies) to offer online, non-wagering social gaming where no money or anything of value is won by the player,” the gambling commission said in a statement responding to questions from the Globe. “This rapidly evolving technology is not gambling, and does not currently fall under our — or any — regulatory authority.”
Still, the commission said it was carefully following new developments.
“We continue to closely monitor the introduction of new gaming trends and we will take the appropriate steps when and if necessary to ensure the integrity of the state’s gaming industry,” the commission said.
In a report to the state Legislature earlier this year, the commission urged a broad approach to emerging forms of gambling and game-playing, including fantasy sports.
The state needs a “regulatory strategy that is broad enough and flexible enough to adapt to any and all of these proliferating games,” the panel wrote.
The Massachusetts Council on Compulsive Gambling declined to comment. But Keith Whyte, executive director of the National Council on Problem Gambling, said online slot machines pose a risk.
“Social gaming raises concerns because there is still a risk of using it compulsively,” Whyte said. “It is the action of gambling that is addictive, not the prizes.”
At Plainridge last week, patrons expressed an array of opinions about online slot machines. Ken MacLeod, of Attleboro, said the low stakes made it more relaxing.
“You get to enjoy playing slots without losing money,” he said. “It doesn’t cost you anything.”
But Kent Kelleher, also of Attleboro, said he won’t play online, worried he’ll become hooked by the games’ glitzy charm.
“It’s not good for the brain,” he said. “It can be addictive. I don’t want that. I come here with $30 and spend it and that’s entertainment. Playing on your computer? That’s not good.”
Indeed, even a few minutes on Plainridge's site, which features such games as “Alice and the Mad Tea Party,” “Bier Haus,” and “Raging Rhino,” can be a heady experience.
“Congratulations!” comes the message after a few spins. “You have been awarded an additional 5,000 credits!”
Moments later, another win, and another 10,000 credits.Sean P. Murphy can be reached at firstname.lastname@example.org. Follow him on Twitter @spmurphyboston.