A lot of gamers believe that - by definition - modern games are not suitable for disabled gamers, but Valve Software doesn't seem to share that view.
"Most of the accommodations we make for disabled gamers (closed captioning/subtitles, colorblind mode, in-game pausing in single player, easier difficulty levels, re-mappable keys/buttons, open-microphones, mouse sensitivity settings, use of both mouse and keyboard and gamepads, etc.) stem from functionality added to improve the experience of both able and disabled gamers," Mike Ambinder of Valve Software explained.
Furthermore, Valve is always on the look for new technologies that can improve disabled gamers' experience. "In particular, we're intrigued by the potential of eyetrackers and the eventual ability to let gamers use their eyes as active controller inputs. For example, it may be possible in the future to let the eyes act as a proxy for the mouse cursor, letting gamers transmit navigation and targeting inputs via eye movements. If you couple this approach with the use of blinks or other proxies for button presses, you may remove the need for a mouse and keyboard (or gamepad) all together."