I am working on a game with a friend and it will be similar (hopefully) to games like Core or Roblox. Currently (at time of posting) we are in alpha. We started working on this about two weeks ago. Some things we need to work out are having games people make automatically post in the game and to have the game be stored online instead of in the game to have the game take up a lot less space.

Youtube channel (we will post updates here): https://m.youtube.com/@UltrabrixOfficial

If anyone knows how to do the things we would like in our game above, please share your knowledge!

Not to discourage you, but two weeks in seems a bit early to be worrying about online functionality. If I understand right that you want to make a sandbox, I'd focus on creating that first :-)
I'd guess step 1. is saving and loading the games you create locally, step 2. getting a server and making an API to send the save files back and forth... I'll admit I only have web app experience with sending relatively small files like xmls, it's probably more complicated for online games.

    housatic yes, i will be getting into that later on. it would be nice to know how to do these things so i don’t have to ask around when it comes the time