O Fortnite, let me count the ways in which I hate thee. And if you have no idea what Fortnite is, count yourself lucky. It’s this summer’s object of moral panic, an online shoot-’em-up game wildly popular among teenagers and tweenies (and England footballers out in Russia). If you haven’t seen anyone actually playing it then the chances are you’ve seen a child doing the floss, the frenetic dance move the game’s avatars can use as a victory celebration. But it’s what they’re celebrating that has parents worried.

Playing war games is a pastime as old as childhood itself, of course, from tin soldiers and pop guns to Action Man and Nerf battles. Parental resistance is useless; when a well-meaning friend banned toy guns, her children defiantly ate their toast into pistol shapes to fire at each other over breakfast. But there’s a rather more disturbing feel to Fortnite, with its faintly Hunger Games-style premise that players parachute on to a cartoon island where their sole task – either alone or in a squad – is to kill anyone they meet, until there’s only one shooter left standing. There’s no blood or gore, so it has a 12 rating. But it’s hard to feel good, all the same, about an immersive game putting a child into the shoes of a sniper. We have reached an uneasy truce in my house, where Fortnite isn’t banned but it is rationed – although arguably not strictly enough.

For what singles Fortnite out from other games is the addictive quality it shares with some nonviolent social media apps, and the compulsive behaviour that both seem to encourage in some children. A nine-year-old British girl reportedly wet herself rather than stop playing long enough to go to the loo, hitting her father when he tried to make her stop. School-gate gossip about kids creeping downstairs in the night for a sneaky go while everyone’s asleep, or parents having to physically pull the plug to stop them playing, is rife. What makes it so gripping is partly the fact that the action unfolds live. Unlike other computer games (not to mention a book, or a good old-fashioned board game), you can’t hit pause and come back later; put the console down even for a second, and someone will kill you. As with Snapchat streaks or chain letters, there’s a powerful built-in incentive to keep it going, which seems unlikely to be accidental.

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And the bitter lesson from alcohol, tobacco and sugar is that addictive substances are more dangerous for some than others. Some adults can easily stop halfway down a bottle of wine; others really can’t. Some people can have just one square of chocolate, others have to finish the bar. Most kids will be obsessed with Fortnite for a while and then get bored, just as they once did with loom bands or Fireman Sam or any other passing craze; but others won’t move on so easily. As with other addictive substances, the lonely, the troubled and those trying to fill an emotional need may be more at risk. And with all due respect to the guest on Radio 4’s Today programme complaining that even when she took her sons to Barbados they just wanted to go on Fortnite, the problem isn’t middle-class kids failing to appreciate expensive holidays. It’s kids hooked on screens in homes where nobody’s even trying to turn them off.

Simon Stevens, the head of NHS England, rightly warned this week against the twin threats of childhood obesity and social media fuelling anxiety; they’re inextricably linked. Kids spending hours on the Xbox have less time for calorie-burning physical play or seeing friends in real life. Toddlers permanently glued to iPads aren’t getting enough adult interaction, and teenagers addicted to their phones are often short on sleep. It’s not the act of staring at a screen itself that matters so much as all the other things you’re not doing as a result, as any adult who can’t drag themselves off Twitter will know; and as with all addictions, the red flag is when it’s getting in the way of a normal life.

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Sensible parenting should go a long way to solving the problem, obviously, but that doesn’t help the children of parents who have either never learned to say no or are overwhelmed by their circumstances. Instagram and Fortnite are free, and there’s not much tweens will happily do for hours that costs no money. There is a reason that effective regulation of booze, fags and sugar has generally involved taking control out of parental hands. But the public health repertoire of age restrictions at point of sale, or “sin taxes”, don’t transfer easily to free online games and apps.

What’s left is piling pressure on industry, making it commercially risky for them to ignore their social responsibilities. Can they really not devise more viral kids’ games that don’t revolve around killing (and would the answer change if more developers were female)? Given how much they know about users’ behaviour, can’t social media platforms do more to identify young children opening accounts below the age limit of 13?

And now that we understand more about Facebook’s addictive design features, it’s time to identify similar aspects of gaming that may be encouraging children in particular to overdo it, just as happy-hour promotions and dirt-cheap supermarket booze promotions make binge-drinking more likely. There’s nothing wrong with creating a product kids want to use. But deliberately trying to get them hooked crosses an ethical line, which is why the concerns raised by Fortnite will be around long after the game itself has fallen out of fashion.

• Gaby Hinsliff is a Guardian columnist