Limit yourself to a game with over 1,000,000 million registered users, or a game that has been around for 10+ years.
Rocket League is an arena soccer driving game (yes, not a genre) that has cars! And good reviews.
Minecraft and Terraria are two sandbox games with building elements. I believe there are some other popular sandbox games out there.
I fully-recommend Agar.io !
Generally if one person is really hyped about one game then everyone plays it! But if it's an MMO then try to stick to popular ones that won't get shutdown.






