Over the past few weeks, gamers in China have become obsessed with a free-roaming Japanese frog.
Travel Frog has topped the charts of free game category in Apple's App Store in China for more than a fortnight.
The game, developed by Japanese company Hit-Point and originally called Tabikaeru, is only in Japanese, but is easy to play despite the language barrier.
It lets players own a cute little green frog which lives in a hut, where it eats, writes, reads and sharpens pencil - sometimes it dozes over books.
Out in its garden, player can collect clover, the primary currency in the game. You collect 20 clovers once every three hours simply by swiping across the garden, or you buy them with real money if you are too impatient to wait for them to grow.
But the most curious feature of the app is that beyond that, players have very little control of the frog. It will frequently leave its home and travel around Japan on a whim.
Players never know when the frog sets off, when it will get back or what it will bring on its return. Sometimes the frog goes home within a few hours; sometimes it could be gone for as long as four days.
It might send postcards, clovers, souvenirs - or might do absolutely nothing for its owner.
There is no way for the owner to control or interact with the frog.
The only thing that players can do is to prepare food, tools and amulets for the wandering frog.
Chinese players have spent more than $2m on in-app purchases for their frog babies.
In Japan, however, it's been downloaded a mere 400,000 times on the App Store and Google Play combined, with users spending only $100,000.
Some players have related the love of the frog to "toad worship", the surprising fandom around Jiang Zemin, reports BBC.