For playing games with the big buttons, they have to be connected to the computer instead of the wheechair. Here we could be lazy: As described here, one can just use a Arduino Micro or Leonardo as a joystick or gamepad (or just an ordinary keypad). So we just need to make a nice housing, add mono phone jackets for each button and we would be done. But this leaves room for more ideas: Since we can use basically every type of sensor as an input, we might be able to go away from the buttons and add additional sensor types, since game control with just a very few buttons is limited. Simple options are: A gyroscope as kind of joystick (analogue input), and/or air flow sensors as additional input control... But in this case we are in the "its start to get complicated", so that will be thing which is still ongoing in development.