Deaf-Blind computer gaming is something I'm quite ignorant about. I'm not aware of a single deaf-blind gamer who plays computer games. I wonder how many do and of the explored/unexplored possibilities.
I realise that like deafness and blindness, deaf-blindness comes in degrees. Wikipedia's definition is of people with little to no useful hearing and sight. I'm not sure if that's how all Deaf-blind people would define themselves.
One-switch gaming potential can be found in Amateur Radio deaf-blind operators communicating via morse code, receiving information via buzzers they can feel. Games of Hangman, Battleships and Chess could be played in this way. This method of interacting was at least proposed for home computers too, potentially making text games playable. To me this is a curious existential meshing of humans interacting entirely in 0s and 1s with binary computers.
Beyond this, I'm aware of modern day refreshable braille displays, such as the £900 (GBP) Seika Mini Braille. This can open up the modern web to a greater extent and some text based touch typing experiences. But do deaf-blind users play games using this technology? Surely they do.
Mixing these two ways in, there are some definite possibilities for games that are less concerned with language:
• Whack-a-Rat: Someone has a tall pipe, and drops a pretend rat down it. The player has to whack it with a stick when it appears at the bottom. This could be replicated with a count down sequence of buzzes, a randomised pause, then a small buzz as it appears. Your accuracy can be fed back with a score out of five (indicated by one to five longer buzzes). One-switch playable too potentially. Alternatively, you could have a constant buzz, and as soon as the buzz stops you hit SPACE BAR. Your speed could be conveyed in Morse, or you could get a one to five buzz rating for how well you did. Five for best.
• Morse SIMON: Simon says, but with the player having to repeat rhythms, letters, numbers, words or a sentence that builds up depending on the difficulty level selected.
• Matching Pairs: Mix a pool of 13 (or 18) matching pairs of unique sounds which have distinct vibration patterns. Assign them randomly to A-Z and optionally the number keys. The player has to find the matching vibrations by tapping two keys on the keyboard. The more mistakes in finding a match, the lower they score.
• Action/Adventure: Hybrid action and text games are a possibility. One thought for a horror/ghost-story element of a game could be... Describe an environment in text and morse, then turn to creating the rhythm of some footsteps that vary in intensity and regularity, maybe some thudding too... the game gives a cue such as "get ready" in text and morse.... When you hear a panic buzz, mash your button to fend off the attacker... Then text descriptions resume. The interface could be as simple as learning Y/N on the keyboard or in morse. Here's some weird-stuff slightly related about communicating with silence at the Enigma Research Group.
Additionally, games that involve real world items, like the football field in the video above, could have many possibilities.
• Guess What?: Could have a real-world box of random objects... press them into a person's hand... they are then asked a question about the item by the computer in morse / braille and have to respond with a Y or N in morse, or press the Y or N on a keyboard. Their score out of ten is buzzed out to them at the end.
I mentioned some of this on the IGDA GASIG forums, and got some fantastic information back from Mathias Nordvall of the Sightlence project, which is an editor for designing haptic signals for computer games. They have created a version of Pong that makes use of two Xbox 360 joypads per player. One pad sits in your lap to indicate the ball's position, the one in the hand indicates the bat position. A full explanation on how to play is given at their site. I'm definitely going to try to find out a bit more on this.
[UPDATE: That didn't take long. See Renée K. Walker's post on life as a Deafblind game player for at least one perspective. Dotris, a braille version of Tetris you can feel via Ian Hamilton. Web-navigation in Morse via Thomas Westin, and a Catch the Car idea from Richard Hayden using sound/vibrations].