The hottest smartphone game in China is a game that you barely need to play at all.

Tabikaeru: Journey Frog is about a Japanese pet frog that doesn’t interact much with its owner. There are only two scenes: A house and a courtyard outside. You collect clover leaves from the courtyard and use them to buy things for the frog while he chills in the house, eating or reading whatever he wants.

You also need to pack up food and tools for the frog, allowing it to set out and travel to a range of Japanese tourist sites. In return, it will send souvenirs and snapshots to you… if it feels like it.

You see, the decision about when to leave and how much to send back is entirely up to the frog. And when it’s away, pretty much the only thing you can do is stare at the empty house and wait.

The game is an unusual hit, all the more so given that it’s Japanese. Hit-Point, the company behind the game, said that it only targeted Japanese gamers and didn’t run any large-scale advertising campaigns in China. The game's popularity spread almost entirely through word of mouth.

It’s not the company’s first viral hit. Hit-Point also created Neko Atsume, an addictive cat-collecting game for Android and iOS, released in 2014.

On social media platforms like WeChat and Weibo, players actively share the status of their pet frog, with posts describing “my frog son” and how they feel like “elderly parents waiting for their kids to come home."

On microblogging platform Weibo, the hashtag “Traveling Frog” page now has over 850 million views. Chinese business news outlet Caixin reports that by January 23, roughly two months after the game was launched, it had over 3.6 million downloads on iOS and Android combined.

Chinese media interprets it as a reflection of a “Buddha-like” culture among the country's youth -- referring to a recent viral term that supposedly reflects how China's young people, in response to intense pressure from society, have become more casual and carefree.