"Fortnite" — a free video game where characters fight and build defenses to survive — is the latest gaming phenomenon to sweep the web. But "Fortnite" is about to face a new challenge: The fickle world of mobile gaming, where companies can make a ton of money on a hit game, only to fade into oblivion later. The game started on PC, Playstation 4, Xbox One and Mac, and is now moving to iPhone. Fans of the game say the iPhone launch is a game-changing development that lives up to the other versions of the software. But while PC and console franchises like "Minecraft" and "Call of Duty" have been enduring cash cows, the world of mobile gaming tends to have higher highs and lower lows. "Fortnite's" creators might be wise to keep history in mind as they try to monetize on mobile. The good news for "Fortnite" is that mobile game spending is 2.3 times higher than PC and Mac gaming, and 3.6 times higher than game consoles, according to a recent report from App Annie and IDC. Although only about 35 percent of total apps downloaded are games, games generate about 80 percent of spending in the Google and Apple app stores. iPhone users spend about twice as much on games as Android users, the report said. The bad news is that a short-term payout doesn't guarantee long-term monetary success — just ask the makers of hit games like Puzzle & Dragons and Fruit Ninja, which were among the top mobile games ever as recently as 2015.

GungHo Online Entertainment, which gets about half of its revenue from Apple, had one of the world's best-selling games in Puzzle and Dragons. But since 2013 the company's market valuation has been on a steep decline. Fruit Ninja is still in the top 50 arcade games in the App Store, according to App Annie. But after surpassing a billion downloads during the height of its popularity, the company behind Fruit Ninja may have lost its footing. Last month, Halfbrick put two of its iPhone X projects on indefinite hiatus, in part because of the "financial feasibility of continued development." Some tech blogs have also reported layoffs of up to half the staff at Halfbrick (CNBC has not been able to independently confirm the layoffs.)

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