The beta allows you to play local multiplayer games online.
There’s a lot of criticism lobbied at Valve and their Steam storefront nowadays. Some of it is warranted, some of it probably isn’t, but whatever you want to say about Steam, you can’t say the thing doesn’t get a lot of updates. Today a new, potentially major one entered the beta stage with Remote Play Together.
The program is currently running and is compatible with thousands of games on Steam. It lets players invite friends to join thousands of supported local co-op games. That means that a game doesn’t need to support online specifically, and that only one person needs to have the game installed, with the others connecting through Remote Play Together. Their controllers will act as if they are directly plugged into your computer, with voice chat and game options all available in one place.
Remote Play Together is in beta currently. No word on when it will be out of the beta phase, but you can try it out now via the Steam client. You can read more details through here.