I honestly believe (with all the ignorance I currently possess) that Minecraft is a better option than Roblox because at least with Minecraft your children can play without needing an internet connection. In contrast, Roblox absolutely requires an internet connection to be used, and that brings many dangers. Minecraft is an excellent option for playing solo in creative mode or with friends in survival mode. It's safe, since you don't have to worry about anything without an internet connection.