Most if not all game design methods are universal and not restricted to medium. His first two steps are easy to do in a notebook and the 3rd step is also not difficult to accomplish using Unity, Game Maker, or really any engine like those where pushing out a prototype becomes tedious. However in step 3 where he says "playtest+polish it till I’m sure I can’t improve it" for video games this doesn't mean graphically but mechanically which is very doable.
