In-game purchasing systems, such as 'loot boxes', in popular online games resemble gambling and may pose financial risks for vulnerable players, according to gambling psychology researchers at the University of Adelaide.

The researchers have examined a range of popular online games that include the option of paying small fees ('microtransactions') to access additional features or content that enhance the player's experience.

In an editorial published today in the journal Addiction, the researchers say some online games enable endless spending behaviours and employ systems that disguise or withhold the long-term cost of these microtransactions. The true financial cost of such games may not be obvious until the player is financially or psychologically committed and then finds it more difficult to stop.

"These schemes may entice some players to spend more money than they may have intended or can afford, especially when using credit cards or virtual currency that makes it hard to keep track of spending," says Dr Daniel King, Senior Research Associate in the University of Adelaide's School of Psychology.

He and fellow author Professor Paul Delfabbro, also from the School of Psychology, focus on a purchasing scheme called the 'loot box', an in-game reward system in which players can repeatedly buy a random selection of virtual items. The loot box feature has recently been the subject of regulatory attention across many jurisdictions, with the Belgian Gambling Commission announcing in April this year that loot boxes were an illegal form of gambling.

"Players hoping to win a particular item may end up repeatedly buying loot boxes at significant personal expense," says Dr King. "Because loot boxes require no player skill and have a randomly determined outcome or prize, they function similarly to scratch tickets or gambling slot machines."

The editorial follows the World Health Organization's announcement last week that it plans for the first time to include 'gaming disorder' in its diagnostic manual, the International Classification of Diseases. The authors hope that drawing further attention to these new financial aspects in games may contribute to continuing debates on the nature and extent of gaming-related harms.

The researchers call loot boxes and similar schemes 'predatory monetisation' because they encourage repeated spending using tactics that may involve limited disclosure of the product, unavoidable solicitations, and manipulation of reward outcomes to encourage purchasing behaviours over skilful play.

They liken some of these schemes to a form of psychological 'entrapment' where players spend an escalating amount of money because they believe they have invested too much to quit. There are also sometimes pressuring tactics, incentivising purchases such as so-called 'limited time' offers.

"Some of the top-earning game publishers have registered patents for microtransaction systems that incentivise the player to spend money, but there are few regulations or consumer protections associated with these systems. I think most experienced gamers will agree: gaming should really be about skilful play, not gambling," says Professor Delfabbro.