Big Picture, the mode that transforms Steam into a big-screen service easily controllable with a gamepad, is officially live now, following a beta that began in September. To celebrate, a range of games that fully support controllers are on sale through December 10 at 10 a.m. PT, some for up to 75 percent off.
A few games on sale are Tiny and Big: Grandpa's Leftovers, Castle Crashers, Portal 2 (now with split-screen), Left 4 Dead 2, A Virus Named Tom and Mark of the Ninja. There are more than 30 games on sale, all of them featuring full controller support.
Steam breaks down games into full and partial controller support: There are 41 games with full support and 387 with partial, though on the Big Picture sale page Steam lists 70 with full and 851 with partial, so there may be some hiding in the rafters. All games are accessible in Big Picture mode, though not all support gamepads, of course.