Should parents worry that their kids are playing Fortnite: Battle Royale?

You probably haven't heard of Fortnite: Battle Royale unless, that is, you're one of the many families whose kids have become preoccupied with this candy-hued shoot 'em up in which up to 100 players enter a combat arena and participate in a visceral game of last person standing.

Since its release last September, the game has been downloaded to personal computers and video game consoles more than 40 million times. And given its cheery, cartoonish look, it is reasonable to assume a large chunk of its vast player base is of school-going age.

With so many children devoting hours to Fortnite there are fears it could cross the divide between hobby and obsession - and that its violence, however slapstick, may have an unhealthy impact.

"Many studies… have shown that playing violent video games is associated with real-life aggressive behaviour and less pro-social behaviour," says Catherine Hallissey, a child and educational psychologist based in Cork. "In addition, there is the potential of any highly interesting and rewarding activity, such as video gaming, becoming addictive, leading to family conflict."

Fortnite isn't the first mass online shooter to develop a fanatical following. The current leader of the pack is PlayerUnknown's Battlegrounds, a more realistic - and violent - title, developed by Irishman Brendan Greene and loosely inspired by The Hunger Games and cult Japanese film Battle Royale, in which a group of prepubescents are stranded on an island and instructed to eliminate one another by any means possible.

What sets Fortnite apart is its child-friendly gloss. The game is sparkly and bouncy and participants are encouraged to personalise their characters with gaudy outfits (Santa costumes, dinosaur backpacks and so on). Battles typically last around 20 minutes, meaning a game can easily be squeezed in before homework but also giving it a moreish, one-last-go quality.

It is this aspect of Fortnite - its powerful addictive tendencies - that has prompted alarm, with one Irish mother going on ITV's This Morning show to explain how Fortnite had negatively impacted on her son's behaviour.

"I had to tell him you're not acting the way you normally act," Suzanne Sellman told presenters Holly Willoughby and Phillip Schofield. "The game is so full of energy and adrenaline that when you pull them off, they are screaming at the television, they're hiding, they're calling each other, they are living in it with their friends."

"This reference to cartoonish graphics sounds as though the developers designed it to appeal to the younger age range in the gaming community," says Dublin-based clinical psychotherapist Joanna Fortune. "This is the age range that benefit least from time spent online gaming as they really need (developmentally) to be engaged in the right here, right now and more in-the-moment style of play."

Scare stories about video games have, of course, been ubiquitous since the 80s. Indeed, the parents whose children are playing Fortnite may have alarmed their families when, in their own childhoods, they developed an apparently dependent relationship with their Commodore 64 or SNES.

What's changed is that we now know more about how video games can impact negatively on childhood development.

"There is the issue of opportunity cost where time spent playing an online game is taken from other activities which have been shown to increase happiness such as in-person play, social interaction, physical activity, time spent in nature," says Hallissey.

"I won't allow my own children to play these games for as long as possible."

Irish Independent Technology Editor Adrian Weckler points out that parents have a major role to play in protecting their child from becoming addicted to video games.

"Fortnite is not really more violent than many other games out there but, like any popular game, it can become addictive, especially because it's an interactive game against other players," says Weckler.

"One particular concern for parents is that different time zones can result in kids staying up later than usual to compete with players based in the US, sometimes eight hours behind our time zone.

"For parents of pre-teen children, this is going to come down to fairly traditional rules around 'screen time' and discipline. For parents of teens, it's going to be trickier, especially if the teens are allowed to have their phones or tablets in their rooms at night."

A related concern is the tendency of children to become obsessed with a particular niche subject in childhood. The stereotypical example is the six-year-old who can correctly pronounce the names of 50 dinosaurs and will roll their eyes when you confuse the Triassic and Jurassic geologic periods. One in three children is thought to develop this sort of intense interest, according to American studies - typically between the ages of two and six and with boys more likely to be affected than girls.

These obsessions usually begin to fade with the onset of 'middle childhood', typically identified as beginning around age seven or eight. Nonetheless, the evidence is that an intense childhood interest in dinosaurs, trains, the planets etc augers well for cognitive development.

"Sustaining interests on conceptual domains can lead to a number of benefits for learning -increased knowledge and persistence heightened attention, and deeper levels of processing," a 2008 report in the Cognitive Development journal surmised.

There is less agreement over the longer-term impact of exposure to video games. A 2014 study by Christopher J Ferguson, Professor of Psychology at Stetson University, Florida, found that video-game consumption was linked to a decline in youth violence rates, while an Oxford report suggested that time spent playing video games had a more harmful impact than the kind of game being played.

"We can see links between some types of games and children's behaviour, as well as time spent playing," said the Oxford researchers. "However, we cannot say that gameplay causes good or bad behaviour. We also know that the risks attached to game-playing are small...

"A range of other factors in a child's life will influence their behaviour more as this research suggests that playing electronic games may be a statistically significant but minor factor in how children progress academically or in their emotional well-being."

Still, few would disagree that endless hours spent crouched over a video-game controller is not conducive to a healthy childhood.

"A 2012 study used brain scans to show that playing violent video games has the potential to desensitise gamers to real-life violence and suffering," says Hallissey. "When that is combined with the still-developing frontal lobe of adolescents, the negative potential is increased. The US Army uses these types of games to recruit soldiers [and] to train them."