Almost every video game is designed to make you want to play it. Fortnite, though, is especially good at keeping people coming back, week after week, match after match. This "stickiness", as game designers call it, is not down to some revolutionary new game design factor. Instead, Fornite has improved and repackaged ideas, creating an effective evolutionary step rather than a leap. While improving shooting skills and chasing a Victory Royale is satisfying, what keeps Fortnite players engaged second-to-second is loot, the items and weapons that can be found all around the map.

Fortnite fans are willing to pay well over the odds for physical copies of the hugely-successful video game, with some discs selling for as much as £750 ($999) on eBay and Amazon. The popular shooter is now available as a free download on a slew of devices, including Sony PS4, Windows PC, Xbox One, iOS and Nintendo Switch. Unlike the physical copy sold in stores, the digital download is free-to-play. The physical copies include a'Save the World' mode which can be downloaded onto digital versions for £30 ($40). A limited number of physical copies of the game were released worldwide last year, and surviving discs are now selling for hundreds online.