Can someone fill me in on how it works.

I only know limited details but think it's along the lines of you play this game and collect coins.

My son said his coins were hacked yesterday and seemed upset.

Is there anything to look out for with kids playing these games.

Thanks for posting this, I will be following with interest.  My 6-year-old loves it and is on it a lot.  The games he particularly loves are Brookhaven and Friday Night Funkin', plus where he seems to want to be adopted!  The chat function is helping him improve his writing and vocabulary (but not his spelling, as anything goes!) and his keyboard skills.  He's even started picking up some Spanish.  The chat seems to be automatically moderated as even the most modest of bad language gets #####.

 

I haven't bought him any Robux yet, but I think I will have to relent soon, as he's getting frustrated being a Noob with "bacon hair".  

 

Would be great to hear from parents with older kids as I'm sure there are some downsides.