It's great and all that you list the keys in the pause menu, but you can't change them. WASD is (for a lot of people) unplayable or impossible to use (for those poor sods with azerty keyboards).

It's also perhaps the easiest thing to implement in the game usability spectrum. If games on a 32K machine in the 80s could manage it, isn't it a tad embarrassing that a game in 2016 can't.