After nearly three months in beta mode, Steam is making its free “Big Picture” mode available to public, giving PC gamers a new option for playing PC games on large-screen displays such as TV sets.

To help celebrate, Bellevue-based Steam is putting on a “Big Picture Celebration Sale” with several of the company’s controller-friendly games discounted by as much as 75 percent. The sale ends Dec. 10.

The Big Picture platform part of a broader effort by the company to push the boundaries of its business and the video-game industry, as documented in this story by the Nick Wingfield of the New York Times, including a first-hand experience with the company’s augmented-reality gaming prototypes.

The new Big Picture mode adjusts the Steam interface for the large screen, but the neat trick is that it also works with existing console controllers. Users can hook up their PC or Mac to a TV with an HDMI cable. Big Picture also includes a new web browser.

Previously on GeekWire: Valve seeks testers for upcoming games and hardware prototypes