Maybe you've already heard of this game and thought its too good to be true. Well, that depends how much your time is worth.
The basic premise is that you play very simple classic games on a browser game and you earn Ethereum, Dogecoin, Bitcoin or their own currency called Rollercoin. You are later allowed to cash out the cryptocurrency you've earned.
At first I was confused regarding this as it was described as a mining game, does it mine from your browser? Thankfully, no. Its simply part of the games GUI that your character is sitting there mining. The game also encourages you to purchase miners within the game that allow you to earn crypto faster, but they are so expensive and slow I would advice against buying them unless you do this for the long term.
The second biggest drawback with this game -- Its extremely slow. You need to keep going playing these games through several days in a row not to fall behind in the earnings and the minimum payouts will take you a few months at least unless you're a very dedicated player.
In short, this game is fun if you enjoy wasting time anyways but nothing to bother with if you seriously want to earn crypto. Then you should look at your options for mining or other suggestions mentioned in other articles I've written.