Phone games that pay you money - how does that work?

Or I guess I should ask, how is it supposed to work? Since I’m sure it’s a scam.

Every so often I’ll get an ad on my phone for some sort of game that is allegedly free, has no ads, and pays you to play. Seems like a guaranteed money losing combination! If the game is free and there are no ads, where’s the revenue stream coming from? In-app purchases? And there’s no way they are paying out $250 or $350 or whatever ridiculous amount they show in the ads . It can’t be more than pennies would be my guess.

So what’s the straight dope on these games?

WAG, you’ll have to pay something before you’ll be able to win anything, or at least anything substantial.

Looking at the first site that popped up when I went looking for more info, here’s some snippets:

After accidentally spending a jaw-dropping two hours playing it (whoops), I earned a grand total of 842 gems. This was enough to purchase me not one, but two 50c Amazon gift cards.

I earned 19,450 points before giving up [after an hour]. I needed 45,000 points to earn the minimum, which was a $5 Amazon gift card.

you have to deposit at least $5 to enter the tournaments that let you win money. Unbelievable. Embarrassingly, I played for 20 minutes before I realized this. Basically, you can earn money playing games by first paying money to play games with this app, AKA gambling.

But you have to deposit money first to enter the games where there’s a chance to win actual money. [snip] I’d have to play for over seven calendar years straight to earn the $100

To be fair, the reviewer isn’t against playing the games, just saying that it’s not going to make you any real money.