In order to design a controller, we first need to know what sort of game is going to be played. I am going to explain how to make a game where the player is told a letter, and they have to press the button of that letter as quickly as possible. They then are told another letter. The player has to hit as many buttons correctly as they can in a 30 second time limit.
There are many ways in which this game can be varied; instead of ordering the player to press a particular button, the game could ask the player a multiple-choice question, and instead of colors, the buttons could be labeled with
Maybe or different colors. You could give the player multiple commands at once, and make sure that they press all the buttons ...