https://thenextweb.com/gaming/2019/10/10/steam-remote-play-together/

Steam is finding a way to take local multiplayer online, apparently recognizing that sometimes couch co-op isn’t an option. This new option will allow users to play any kind of multiplayer game without the other person needing to be in the same room.

Valve revealed the feature, called Remote Play Together on the Steamworks website, which is only accessible to developers. PC Gamer later revealed its existence to the rest of us. Valve’s Alden Kroll described it as such on Twitter: “This will allow friends to play local co-op games together over the internet as though they were in the same room together.”