Since 2017-10-31, Discord Rich Presence has now made its way to stable!
This means that you can now advertise and join osu! multiplayer games from inside Discord servers, see what your friends are playing on osu!, and even ask to join games currently in progress! You can also spectate people who you share servers with.
Gamessection of the Discord options menu.
Display currently running game as status messageoption in the
Gamestab. This is not needed to join games that are advertised by others, but it is needed to advertise your own.
Here's a video of it in action.
If you make a room with a password, people that use your invite don't need to enter anything. Private games at the click of a button with no fuss!
You can also click on the Discord profiles of anyone you share a server with who is playing osu!, and see what they're up to at a glance. If you're friends with them on Discord, you can even ask to join their current multiplayer match.
This button will automagically change to allow you to spectate people who are playing maps currently as well, so never miss out on your friends failing the same song repeatedly again!
If you send Discord Rich Presence invites too often, you may be temporarily faced with an error from Discord that looks like this:
This is perfectly normal and more misleading on Discord's part than anything else. Wait a few minutes, and you should be fine to send invitations again.