Today valve announced steam OS linux based operating system for pc and tv means steam is coming soon in your living room . it simply means users can enjoy  3000+ games , now not all games are available for linux but near in future they will be . 

As we’ve been working on bringing Steam to the living room, we’ve come to the conclusion that the
environment best suited to delivering value to customers is an operating system built around Steam itself.
SteamOS combines the rock-solid architecture of Linux with a gaming experience built for the big screen.
It will be available soon as a free stand-alone operating system for living room machines.

Steam OS is from valve it doesn’t means its just for gamers it will also have Music, TV, Movies etc . a cloud based sysc system will keep all your favorites in the cloud and will sync with you all devices  automatically .
and they mentioned clearly that steam OS will be free . check that announcement  by valve