FIL neglects his grandkids to play some bitcoin earning game?

We don’t know what the game is, but we’re trying to figure out if it’s a scam or not.

My husband’s dad spends hours playing something that looks like Candy Crush, even when we’re visiting with his grandkids.

According to him, by sitting through the game’s ads, he earns a share of the ad revenue in the form of bitcoin.

Is this a thing? Is it legit? Does anyone know which game he’s playing? (We swear it often features a king, as we’ve seen glimpses of a bearded man wearing a crown.)