Steam’s Remote Play Together was officially released on 10/31/2019.
https://store.steampowered.com/remoteplay/?l=japanese 
 
The service has the ability to utilize “online” mode while on “local.”
This may sound like a contradiction but it truly is as described above; allow me to explain.
 
Steam is a major video game distribution platform with over thirty thousand games registered.
Within the registered games, there are a large number of games with online mode that has local only multiplayer mode as well.
Up until this point, if gamers wanted to do a local multiplayer mode, the player who owns the game would either physically bring their computer to the other gamers location or login from a different computer. But with the Remote Play Together, as long as there is an internet connection, a local multiplayer is possible in separate locations.
 
To get the service going:

1. The host send the game screen to the guest
2. The guest input is then sent to the host
3. The host unlocks the input that was sent, and repeat to reflect the game back

 
It is a wonderful service but there are a few things to keep in mind:

• The host computer will need some relatively good specs (in order to process the data to and from the guest)
• The host connection would need to be good as well (it works as a shared screen so if the hosts connection is bad, there will be lags)

Despite these few things, the local multiplayer mode that hasn’t very realistic is now easily available!
Oh, and when using local multiplayer, as long as the host computer owns the game, the guest will not need to purchase it themselves. Being able to use just one is very useful for missions.
 
There have been several games that where only available through local multiplayer that I really wanted to try out (like Super Bunny Man or Cuphead)
But now we have the chance to try out all kinds of games that was out of our reach!
 
If you have a chance, please try it out!