Valve's third and final "big announcement" for this week is a new controller designed to work with Steam OS and its SteamOS-based hardware. The controller features two trackpads (instead of thumbsticks) that uses haptic feedback, a touch-enabled surface with a high resolution screen similar to what Sony is offering on the PS4 controller (which can also be used like four separate clickable buttons), shoulder buttons, four face buttons, and three buttons below the touch enabled surface.
"The most prominent elements of the Steam controller are its two circular trackpads. Driven by the player’s thumbs, each one has a high-resolution trackpad as its base. It is also clickable, allowing the entire surface to act as a button. The trackpads allow far higher fidelity input than has previously been possible with traditional handheld controllers. Steam gamers, who are used to the input associated with PCs, will appreciate that the Steam Controller’s resolution approaches that of a desktop mouse."
Valve says that the unique nature of the track pads make it so that genres that were previously difficult to play using a controller are now supported such as RTS games.
As for the touch-enabled surface at the center of the controller, Valve says that it is required to support all the games in steam's vast catalog of games.
"This surface, too, is critical to achieving the controller’s primary goal - supporting all games in the Steam catalog. The screen allows an infinite number of discrete actions to be made available to the player, without requiring an infinite number of physical buttons."
Valve also claims that every button on the controller has been placed based on "frequency of use, precision required and ergonomic comfort."
All told, Valve claims that there sixteen buttons on the Steam Controller, half of which are accessible to the player without requiring thumbs to be lifted from the trackpads, including two on the back.
"All controls and buttons have been placed symmetrically, making left or right handedness switchable via a software config checkbox."
Finally, the controller features a "Legacy Mode" to support older games.
"In order to support the full catalog of existing Steam games (none of which were built with the Steam Controller in mind), we have built in a legacy mode that allows the controller to present itself as a keyboard and mouse. The Steam Community can use the configuration tool to create and share bindings for their favorite games. Players can choose from a list of the most popular configurations."
You can learn more about the new controller here.