Half-Life 3 will not be on SteamOS or Steam machines only
Valve has confirmed that it won't be making games that are SteamOS or Steam machine exclusives. That means when Half-Life 3 arrives it will be available, hopefully, on all platforms.
IGN spoke with Valve's Greg Comer who revealed the company's plan to remain open for gamers, no matter what system they're using. "You won’t see an exclusive killer app for SteamOS from us. We’re not going to be doing that kind of thing," he said.
Valve’s Anna Sweet went on: “Whenever we talk to third-party partners, we encourage them to put their games in as many places as possible, including not on our platforms," she said. "Because we think that customers are everywhere, and they want to put their games wherever customers are. That would go against our whole philosophy, to launch something that’s exclusive to SteamOS or Steam machines."
Valve did note that some resource-short developers may only be able to create titles from one platform, which will end up as a SteamOS exclusive, but that's not forced upon them.
Valve is due to reveal its hardware partners for the Steam machines at CES in January 2014.