iPhones and tablets have been a boon to game manufacturers -- and parents.
An obstreperous child can quickly become compliant when allowed to play a game on a mobile device.
But now, some experts are warning that some games might be "addictive" and may be "grooming" kids to be future gamblers.
Chandler Gotfried is a freshman at the University of Oregon.
"Three years ago I was playing Tiny Tower."
He was 15 and living at home in Brookings. He says he would spend hours on the game, building his own virtual town.
"It's got like bowling alleys, cinemas, private eyes, doctors' offices."
He enjoyed taking care of the little characters that inhabited his town. But he says, he got in trouble buying something called "Tower Bucks," which he needed to build a big hotel.
Chandler Gotfried: "Trying to do that. I really spent some money on that."
Kristian Foden-Vencil: "Did you ever find yourself getting worried? Like I need to back off this?"
Chandler Gotfried: "Yes. Oh yes. Because when you start getting sucked in you're like okay, I'm going to buy this, and I'm going to spend it on this. And then you don't think about it. And you think. Oh, yeah. I have this much money in there and then end up coming up later you just spent $50, $70 and you're like 'wow, I could have done a lot more important stuff with that'."
Gotfried says he gave it up after his folks found out.
"My mom was like, 'Okay, your credit card bill? Hey, What's going on here?' And I'm like, 'Oh, sorry.'"
Tiny Towers is by no means an unusual game. Other games make money by offering similar online services.
Elizabeth Wooley is the founder of On-Line Gamers Anonymous. She says research by Iowa State University shows about eight percent of children are susceptible to pathological video game use.
"Somebody with ADD is very vulnerable to these games. ADHD, the creative kinds, more of the introverts. They can just get sucked into these games and it becomes their lives."
Just to be clear, there is no formal diagnosis of video game "addiction."
A proposal to include it in the next Diagnosis and Statistical Manual of Mental Disorders - or DSM - was rejected.
Nimblebit LLC, which owns Tiny Tower, did not respond to OPB for comment, after a couple of weeks of e-mails.
Losing money you have to pay back to your mom -- as Chandler Gotfried did -- is one problem. But health experts are worried that getting absorbed in some games could lead to bigger problems in adulthood.
Julie Hynes is an analyst with Lane County Public Health. She teaches a gambling prevention class to University of Oregon students. She starts with a quiz. First up is senior Sara Marcotte.
"Now, we get to have a little bit of fun.
"What are the odds of winning or sharing the powerball jackpot in any drawing. Good thing is, it's multiple choice. One in 175, one in 175 thousand, one in 175 million or one in 175 billion."
What do you think?
Sara Marcotte: "I don't know, one in 175 million?"
Julie Hynes: "One-in-175 million is correct. give Sarah a hand. Nice work Sarah. And the odds of being hit by lightning depending on what state you live in and what kind of statistics you look at are around one-in-280,000."
The message she's trying to get across is: you're more than 600 times more likely to be hit by lightning than to win the lottery.
She hopes such nuggets will teach students that gambling should to be treated as a game -- and not as a way to strike it rich.
She says it's a hard message when children are playing free gambling games on tablets and mobile phones.
"What they are downloading are -- 'World Series Of Poker,' various different types of games that typically are harmless but can often be sort of grooming them for later gambling in life."
These online games award players points or fake money, so they're completely legal.
But Hynes says they teach kids how to play card games like Texas Hold 'em and Blackjack.
"Most of the time it probably doesn't turn into problematic behavior. But we do know from our research with alcohol and tobacco that things like candy cigarettes ended up grooming young people to then think it was cool and want to smoke. We see this as a similar type of example and in fact we do know that many teens in Oregon are indeed playing for free online. We do know that from other research that early initiation of gambling behavior then increases the risk of problems later on in life."
The 2012 Oregon Student Wellness Survey found that 37 percent of Oregon eighth graders engaged in some form of gambling during the previous 30 days -- buying lottery tickets, betting on a sports teams and gambling on the internet.
There's another issue too, says Dr. Jeff Derevensky. He's the director of the International Centre for Youth Gambling Problems in Canada.
He cites research that found some free games have higher odds of winning than their real gambling counterparts.
"So if you're a youngster and you were trying to play these games for fun and they show you how many virtual tokens you've won, or how much money that you would have actually won had you being playing for real money, you're more likely to want to engage in this behavior."
When questioned about free gambling games and concerns about "grooming" children, the American Gaming Association issued a statement. It said, just a handful of its members are involved with online gambling apps, so the association cannot comment.
But the association's website says it has an effort to educate the public about the odds of games and how to make responsible gambling decisions.
Caesars Interactive Entertainment, which owns the "World Series of Poker" game, also issued a statement.
It said: “We operate our social games business and brands to be successful on their own – not as marketing or advertising tools for our casino business and brands."
It also said its social games are intended for adults 18 and older.
Meanwhile, the International Center for Youth Gambling has a list of warning signs for parents.
If your child has unexplained absences from school, dropping grades, a sudden influx of unexpected money, or he or she starts stealing, you might want to seek help.