Scratch

I have thought about it and MMOs are not possible with just cloud variables between same project instances (technically, they are, but there would be way too many security flaws). My suggestion is to let us use cloud variables to and from different projects (server and client) so that we can make servers to specifically handle this variables. I don't think I explained this too well, so I will add some information below.

Why is it "not possible?"
It is possible. The problem is that if variables are handled by the client, the player has full control of them either by exploiting a glitch or directly editing RAM addresses and changing variables. This is inferring the best case scenario: that users are not able to edit variables on the cloud without the need of external tools (such as Cheat Engine) or the code.

Huh? They can't edit cloud variables. They are stored in Scratch server, not in the client.
That is true. However, they can edit local variables which are factors of cloud variables. Think of it this way: You are making a wall in an MMO so that people can't get over it unless they are, say, level 10. They could easily use these external tools to change their position to some place over the wall and this position would then get sent to cloud variables and further more, to other players.

Oh, I see what you mean. Then how would your suggestion help at all?
If the ST were to make a Scratch Server, this is how it would work...
1) The client tells the server that it wants to join the game.
2) The server says, "Ok!" and sends the stored coordinates of the user.
3)The client moves their player to the specified coordinates and attempts to update its position regularly.
4) The server follows the player to make sure it does the right movements. From this step, two things can happen:
  a) The player's movement is valid (has moved at the right speed in the expected amount of time) in which case, the server updates the position of this player for everyone else and stores it itself or
  b) The player's movement is invalid (has moved to an unreachable place or has moved faster than the expected amount of time) and the server returns the player to the last valid position. This would happen if the player is trying to cheat.

Ok, now tell me how it would be done.
It would actually be pretty simple. Just create a special instance of Scratch to run as a server with the ability to manage variables on the cloud or just let two different projects manage the same cloud variables. Both would have the same effect.

If you have any questions, let me know below. Feedback is really appreciated, I want to know what everyone thinks about this and any inefficiencies that I may not have spotted. Also be aware that any of this may change or be erroneous, as 2.0 is not out yet and I am not an ALPHA tester.