This prototype is based on an idea by Rick Buter. After observing Marijn he came up with this idea where you only need six keys to type all common Latin letters, including the most common punctuation.
It’s a prototype. A common keyboard is more powerful.
You can change the keyboard layout in js.js, or by using the keys querystring in the URL. For instance: https://vasilisvg.github.io/six-key-typing/?keys=asdjkl