My nephew (8 years old) had been addicted to Roblox and it's insanely popular among his generation, it appears like they all play the shit out of it. It's free-to-play so the entry barrier is very low, aso the mechanics in some of the games there are not too bad, actually. However, he got scammed one day. Suddenly the game stopped working and an error message popped up that said 'click here if you want it function properly again' so he clicked and it turns out that he installed a virus instead. It still didn't work so he showed this to his dad (my brother).
At the end of the day my brother telephoned with a guy from what appeared to be the customer service, but it was actually the scammer himself who demanded his accounts from amazon, his e-mail, his ebay, his paypal and so on because the scammer told him that the virus was spreading into these accounts already and he wanted to check if some damage was alreadys done. My brother got suspicious and hung up. He was just a few clicks away from giving that motherfucker the access to all of his acocunts.
My nephew never played that shit ever again, they uninstalled it on that same day and he gave his dad 10€ from his own pocket money in remorse. So while Roblox might be cool to the kids, it is quite dangerous actually. There are a lot of criminal activities going on there, you can google it.