Steam has been experimenting with an in-home streaming feature that allows you to host a game on one machine and play it on another. Now, that feature is out of beta and it's releasing on time, for everyone.
According to Steam, you simply need to log in to two different computers on the same network. You'll then be able to see your library on different machines and remotely install, launch and play them from any device. You can read more about the service at the source link below.