Reposting for the sake of clearing it up for those confused.
I'm seeing some confusion here.
You do not need two PCs to play games using SteamOS.
You know how some games support MacOS, and some games only support Windows? SteamOS will be exactly the same.
Some games will support SteamOS natively.
Some games will not.
If your game
does support SteamOS, you can install it
directly to the device, just as you do with Steam now, just as you download games to your gaming consoles, and just as you install games to your smartphones. SteamOS supported games will be purchasable, downloadable, installable, and playable right from the source.
If your game
does not support SteamOS, you can install it to a Windows or Mac device as we currently do, and
stream the game over a local network to a SteamOS device. So if I had a SteamOS box in my lounge room, but a game that does not support SteamOS, I could turn on my Windows 7 PC in my bedroom, turn on Steam, install the game there, and play it in the lounge room on my SteamOS device by streaming data over the network from my PC.
Though this will obviously be problematic for games that
don't support SteamOS, Valve has made a point that they're working closely with developers to ensure games
do work with SteamOS. And if a game is native to SteamOS, it can be installed directly to a SteamOS device. Absolutely zero streaming required. Examples, going by the SteamOS home page: Total War: Rome II and Metro: Last Light.
Bleh, those FPS numbers are already huge that the FPS gain is somewhat masking. % change would be a more valid metric for me, which in this case seems to be 10-20%. Not trivial, no, but would also like to see this optimization on a non-Valve title for a variety of reasons.
Completely agree. To be fair though, that report was from August 2012. Who knows what strides they've made in 12+ months.
What about other games not running on source engine?
We don't know. The report was from over a year ago, and just to show Valve was experimenting with OpenGL performance under Linux, at the time assumed to show the benefits of running Linux Steam (which has been around for awhile now) versus Windows and Mac.
Unless the SteamBox is as good as your PC why would you play Metro on it? And if it is, how much are you spending to have two equally powerful PCs?
This is like an extremely expensive HDMI cable.
You wouldn't. SteamOS is not for people who already have high end gaming machines they're happy with. SteamOS is for integrating a gaming operating system into lounge room devices. Metro: Last Light is simply an example from Valve of a game that will support native SteamOS, and thus be purchasable without streaming for anybody running a SteamOS device.