Chances are, at some point, you've been that person avidly playing Candy Crush on the tube. Or, if you haven't, you've probably sat mesmerised watching someone else play it over their shoulder.
The addictive nature of "freemium" games like Candy Crush, which are free to initially download but encourage in-app purchases, is well-known to commuters, but new research from Go Compare Money has shown one in 10 adults (11 per cent) say they are addicted to at least one such game app.
In 2014, free games with in-app purchases made up 92 per cent of the total revenue from the games category on the Apple App Store.
The highest grossing game on the Apple App Store in March 2016 was Game of War – Fire Age which made a staggering £1,088,463 per day.
Other popular examples of freemium games include Clash of Clans (£859,643 per day), Mobile Strike (£586,829 per day) and Candy Crush Saga (£300,523 per day).
Londoners spent the second most in the UK on in-app purchases, which are often linked to progressing to later levels or on special features within games, with an average spend of £26.80, while Northern Ireland reported spending the most at £32.66.
The average spend on in-game purchases in the UK is £18.62.
Eight per cent of adults have also admitted to playing mobile games at work, while nearly one in 10 (nine per cent) of parents have their card details registered on their child's phone for purchases.
"Free-to-play mobile games might seem like something for nothing. However, most of these games are designed to encourage a "just one more" mentality, and with one in ten adults saying they’re addicted to at least one of these games, this can be a dangerous combination when paired with in-app purchases," Matt Sanders, credit card spokesman at Go Compare, said.
"Free games tend to keep in-app purchases fairly cheap, with regular small purchases key to their income. However, while something like a £2.99 purchase once a week may not seem like much, it can add up to over £150 a year and some may find they’re spending a significant amount of money on a "free" game."