Update 17/10: Valve confirmed over email that Remote Play Together will work on Linux.
The Steam pipes are leaking over at Valve again, as an upcoming feature called Remote Play Together is coming during the week of October 21.
Valve sent word just to game developers, which they never keep quiet on for very long. Multiple game developers (#1, #2 and so on) ended up putting out posts on Twitter to let everyone know about it a bit earlier than Valve seems to have intended. Here's what it says (from this image):
We're reaching out to let you know about a new feature heading to Steam
Your local multiplayer games will soon be improved with automatic support for Remote Play Together on Steam. Remote Play Together is a new Steam feature that enables two or more players to enjoy local multiplayer games over the internet, together.We think this feature will be very valuable for customers and developers and are excited about the beta. We've provided an FAQ at the bottom of this message which we think addresses most questions and concerns.
All local multiplayer, local co-op and split-screen games will be automatically included in the Remote Play Together beta, which we plan to launch the week of October 21.
While other services have existed for a while to allow local multiplayer titles to be played with your friends across the net, like Parsec which I tested some time ago for a different purpose, having this built into the Steam client is a fantastic idea. Think of all those fantastic local multiplayer titles you could enjoy all over again, without needing to have someone sat right next to you.
Confirming it's true, Valve developer Alden Kroll explained on Twitter in reply to a question about LAN games:
To clarify: it really is only for shared-screen or split-screen games. The tech is streaming your screen to your friend and capturing their input and sending it back to the game, so you are both playing the same game, looking at the same thing.
You can also see more details in this post on the Unity forum, which shows the bits missing from the linked picture and tweets quoted above. So only one person needs to own the game and you invite others to join you. It's really great to see Valve continue to innovate with the Steam client features.
I think I'm going to enjoy this.