When Microsoft first unveiled a pair of smartcovers with integrated keyboards as a key part of its Windows 8 tablet strategy last week, most commentators saw the move as an attempt to position the tablet computers more directly against standard laptops. But for gamers, the Touch Cover in particular could open up some interesting new control options for PC games, if Microsoft and developers are savvy enough to capitalize on its potential.

The key to the Touch Cover's hidden potential as a new form of game control comes in its keyboard's little-noticed ability to differentiate between various levels of pressure being placed on each key. Microsoft's Panos Patay points out this feature about 41 minutes into the video of the tablet announcement, highlighting how the Touch Cover is "actually measuring every gram of force coming off my fingertips."

In the presentation, this pressure-sensitivity is sold mainly as a way to improve the accuracy and speed of touch-typing when using the cover, as compared to pecking away at a touchscreen keyboard. But a generation of gamers that made the transition from digital directional pads to analog joysticks knows well that measuring fine gradations of input can lead to more precise, sensitive control for a wide variety of games.

A brief history of pressure-sensitive buttons

While joysticks and pointing devices tend to be the most common analog game controllers, there is some precedent for analog buttons in the gaming realm. The earliest versions of the arcade cabinets for 1987's Street Fighter featured two large, pressure-sensitive buttons for Punch and Kick, varying the in-game attack strength based on the physical strength of the player's input (the standard six-button layout reportedly came about after over-enthusiastic players started breaking the cabinets' hydraulics with too much force).

Most developers ignored the analog face buttons built in to the controllers for the PlayStation 2 and original Xbox, though Metal Gear Solid 2 notably let players holster an aimed weapon by slowly easing up the force on the X button. Developers have been more eager to use the analog shoulder buttons on the Xbox 360 and PS3 to support variable throttle and braking in racing games, or precise turning in flight simulators, for example.

But those are handheld console controllers, with spring-loaded buttons designed to be gently squeezed by crooked index fingers. Can similar analog control schemes work on a keyboard? Microsoft already answered that question, to an extent, when it unveiled a prototype for a pressure-sensitive keyboard back in 2009. A demonstration video for the prototype shows that the company had begun tinkering with gaming applications for the technology three years ago. About four minutes into the demo, Microsoft Senior Researcher Paul Dietz shows how the standard WASD and space bar controls in a first-person game could be modified to allow for different walking and running speeds, as well as jump heights, based on how hard each key is depressed. "It really is proportional control, it's almost like having a bunch of joysticks on your keyboard," Dietz points out.

A few more intriguing pressure-sensitive game prototypes came out of Microsoft's UIST Student Innovation Contest that year. BallMeR, for instance, lets players guide a soccer ball by mashing the pressure-sensitive keys to control the height of different parts of the field, offering a level of control that a handheld controller can't match. Two researchers from MIT used the keyboard prototype to create a simple rock-clibming demonstration, where the amount of pressure on four different keys controls the precise angle and pull strength of a rock climber's hands and feet.

Uncertain implementation

When approached by Ars Technica, Microsoft refused to address whether it would be promoting the potential gaming control applications of its tablet Touch Cover, or to confirm whether or not the pressure information from the cover would even be visible to developers working with the tablet (rather than just used by the tablet OS).

Still, some developers we talked to seemed intrigued by the potential to bring analog controls to the digital keyboard.

"When you use a traditional game controller with buttons, you have to map all kinds of different non-binary actions to a binary button controller," Dr. Bennett Foddy, creator of multiple game control experiments including QWOP and GIRP, tells Ars. "Games like Mario Bros. get around this by measuring how long you press the button for—you jump higher if you make a longer press. But I think it would make more intuitive sense, and be more absorbing, if you could jump higher by pressing harder."

But other developers expressed skepticism about whether gamers would really respond to a pressure-sensitive keyboard, or whether it was worth developing applications for a smart cover that will no doubt represent a very small slice of the PC gaming market.

"I wonder how 'juicy' it will feel without the tactile feedback of pressing a button down and hearing that little tap of the key," Johann Sebastian Joust creator Douglas Wilson told Ars. "That kind of kinesthetic and tangible experience is important to making technology 'feel' right. Maybe that's one of the reasons I've never been so excited about the smooth glass screen of tablets"

And even if the pressure-sensitive Touch Cover somehow catches the imagination of a critical mass of game designers and players, that doesn't mean the games that are made for it will be any good. "Looking at other technologies like computer vision, the Kinect, and accelerometers [like] the Wiimote, I think the industry is still having trouble figuring out exactly how best to use them," Wilson continued. "Speaking from personal experience, it took me years of experimentation to formulate an approach to using motion controllers like the Wiimote/Move."