We'll start with the ultimate time sink. If you dig survival games or just like the idea of riding a dino across a prehistoric landscape before building your own city, Ark is up your alley.
You probably already know about Ark, but if you don't, the idea isn't just to fight other survivors and build a settlement, but it's also to tame and domesticate wild animals. From fiery Ark magmasaurs to spidery bloodhunters, creatures of all shapes and sizes can join your primal menagerie when you figure out the proper taming methods.
Yeah, it has some clunky UI and connectivity issues still, but there really isn't any competition when it comes to Ark, a survival sim where you get to build up a stable of animals and craft a society however you please.
To really understand the amount of time you might lose to Ark, just take a gander at the game's Steam page, where hundreds and hundreds of players have logged thousands of hours of play time!
If you're not a fan of the game's prehistoric sci-fi setting, Outlaws Of The Old West has essentially identical gameplay but lets you live out your Wild West fantasies instead.