Valve has announced Steam Machines, a series of living room PCs that run SteamOS.

The PCs will be made by Valve as well as with third party manufacturers.

“Entertainment is not a one-size-fits-all world,” said Valve.

“We want you to be able to choose the hardware that makes sense for you, so we are working with multiple partners to bring a variety of Steam gaming machines to market during 2014, all of them running SteamOS.”

“We have designed a high-performance prototype that’s optimised for gaming, for the living room, and for Steam,” the company added.

“Of course, it’s also completely upgradable and open.”

According to Valve, from the beginning of next year there will be multiple SteamOS machines to choose from, made by different manufacturers.

“The specific machine we're testing is designed for users who want the most control possible over their hardware. Other boxes will optimise for size, price, quietness, or other factors,” it said.

Steam Machine specifications and photos were promised “soon”.

Each will be hackable, and allow hardware changes as well as the installation of a different OS.

Valve is offering 300 free Steam Machines to the community for feedback via a random draw.

“Your help is critical to our design process,” said the company.

“Your feedback will shape both the new OS version of Steam and the new category of gaming machines that will run it.”

Valve said that it would eventually offer downloads of SteamOS including the source code, and that it had "more to say very soon on the topic of input".

The Steam Machines announcement is the second of three promised by the company.

A final announcement from the company is 44 hours from the time of writing – about 4am Saturday morning.