Would like to be able to select multiple users and have a chat conversation with them, similar to group text messages on a phone, without having to create a team and add them as teammates.

Would like to be able to add a "reaction" emoticon to another user's chat message, such as a thumbs up.

Am/pm is not used where I'm from so it's not as intuative for me as 24 hour time format.

One thing we really like would be an added option for custom icons / emoticons.

Of-course this adds nothing to functionality, but I know our team of 8 always loves to play around with it.

When you open a forum after being away, I would like to be able to go to my last unread chat either automatically or by clicking a button or link.

We often find ourselves forgetting/losing track of important posts because they're off in the separate 'Posts' tab rather than right there in the chat channel. As such, a feature that allowed posts (or even just a single post) to be stickied to the top of the chat window would be really useful.
It might be useful to make this an admin-only feature/add an option to only allow admins to do this.

It would be great if we could record a voice message and send it as a chat message. In the app, the chat message would show that there is an audio file and allow you to click to listen to it. Kind of like a mini MP3 embed.

Just a "Bob and Steve are typing" at the bottom of the chat to let the other people know that the person is actually responging.

It would be awesome to have the ability to include inline and displayed maths in chat and posts.

This is becoming a common extension to markdown in academic writing and would set Ryver apart and give you an edge in that market. Currently only Rocket.chat implements this nicely (there's a poorer implementation in Mattermost but it's mostly nonexistent in other apps). There's two well developed javascript libraries already to handle the typesetting: MathJax and KaTeX.

In our Ryver community (ibmioss) we have a lot of chats that get promoted to posts and that is very confusing if you started a chat and it was promoted to a post by somebody else (you wonder "where'd it go?"). I then need to go to the posts tab and start looking. Instead it would be good if an existing chat could be marked as a post and that would start a form of indentation within the chat pane. This means the post tab would go away. This would also necessitate a "Filter" feature on the chat pane (maybe refactored to not be named chat, because posts would also be there) that would allow just posts to be displayed.

I don't want to derail this feature that's already planned. But I did want to convey that the current approach is not immediately intuitive (and even after understanding the feature I still get lost).