If you’re unfamiliar, Roblox is a game on PC, mobile devices, and Xbox One that lets users create their own avatar and play any number of thousands of games that are all created by other players. In addition to playing games online with friends, anyone can also start building their own world and release their very own Roblox game.

The vast majority of games on Roblox are all free-to-play with advertising and microtransactions, similar to games found on the iOS App Store or Google Play. Players can even subscribe to the Roblox Builders club to earn daily credits and other special rewards. Everything in the business model from the games users play and worlds they build to the subscriptions and advertising all feed back into the same gameplay loop of getting eyeballs on the website. It’s a deliciously powerful machine that, according to website-ranking portal Alexa, has been so successful it’s actually earned Roblox.com the 107th most popular spot in the entire United States.

Roblox has reached a popularity level with the young gamer demographic that few developers could ever dream of achieving with their releases. But at the same time, a shocking number of people have never heard of it. As it turns out, games starring player-customized faux-Lego figures just aren’t very popular among adults, but they’ve taken the world by storm for those under the age of 14.

As remarkable as that all sounds it’s anything by an overnight sensation. Roblox, as a platform, has existed for well over a decade and easily surpasses 30 million active users per month with a large fraction of that base also contributing to its growing catalog of content.

That user-generated content idea is often a throwaway feature in a video game. Developers will craft a long, detailed experience with dozens of hours of content and then throw in some modding tools or level creation options to give the illusion of replayability, but in reality you never use them. That’s a big reason why it’s so hard for developers to succeed with games that are seemingly founded upon the idea of world building and creation.

When considering Roblox, it’s important to keep in mind that it isn’t just placing blocks in a virtual world like in Minecraft. In the case of Roblox, you’re opening up a program called “Roblox Studio” and actually building models of objects and characters, you’re creating NPCs and giving them dialog, or even writing some code to make things act a certain way. You could liken Minecraft to a restaurant with a really thorough menu that lets you pick and choose your combo platter, but Roblox is more like the world’s largest buffet, featuring every type of food, but then the kitchen is also open to just make something from scratch instead if you want.

Even though Roblox is designed for kids very carefully and directly that doesn’t mean parents should just let their children play it without any regard for privacy and safety. With the way the internet works if you let loose your underaged child onto a platform that’s powered by and reflective of its community, a community that exists and identifies with the internet as a whole, it’s a risky proposition. Internet Gutter meme culture is rarely PC or kid-appropriate.

Generally speaking, not many parents really have a good idea of what their kids do on the internet these days. Sure, they might know the name of the popular YouTubers they watch the most or have general familiarity with the fact that their teenage son plays World of Warcraft, but the majority of parents aren’t overly engaged with their kids’ online identity. That should absolutely change and Roblox is definitely a risky playground that should be monitored more.

With so many possibilities of what to do, games to play, and worlds to build, it’s no wonder that kids these days can’t get enough of Roblox.