I think we all know that chatrooms aren't allowed on Scratch. I mostly picked up on this idea when I started seeing cloud-based/multiplayer projects using emojis instead of just letting you type. The FAQ also says that:

While it is technically possible to create chat rooms with cloud variables, they are not allowed on the Scratch website.

They also said somewhere that it'd be hard to monitor, but I'm not sure where or if they even stated that in the first place.

However, I do have an idea. On the note that most multiplayer projects with “chatting” often have a selection of emojis/emotes for you to select from, (as far as I know) can't you just make a chatroom with strictly emojis? I mean, that is basically what these projects have in mind for a chat system. Only emojis, no letters or words.

The question here is, “Can you make a chatroom with strictly emojis?”
First, I'd set up a few rules for obvious reasons:

• No emojis with letters, words, or anything that could possibly be used as a letter/word. (This includes glyphs, if there are any i'm not sure.)
  

• No inappropriate emojis, as i'm sure that there are plenty of emojis that are ment to be used inappropriately.
  

• No emojis that could possibly allow people to send hate towards others (This would be hard to do, but maybe it's possible)
  

With these rules in mind (maybe rule 3), Then it might be possible to do so. Theres still things to also keep in mind, like what the Scratch Team thinks about this, and if others think it's okay (because they might think otherwise and report).

Please Read:
I am not asking this question because I want to make a emoji chatroom, I am only asking because I had thought about the idea and was curious.

Yes, it is allowed. There is already a such project, but it stopped working.

Emoji chat is allowed, and even chat with pre-made phrases that you can select.

It's allowed, griffpatch has an emoji chat in one of his games.

Yes, as long as it does not contain the inappropriate (you know what those are) emojis.