First of all, the music is brilliant! It feels like a part of the game, the way it leads in to the start of a run. It also makes the hectic gameplay more relaxing. Speaking of, the gameplay is near perfect, I love the grapple move, it was not what I expected! This is definitely one of the most polished games I have played so far.
I guess I should nitpick some things too. Whenever I go outside of the screen, I lose track of where I am. And there is almost no invincibility period after getting hit, so you can very quickly get killed if you make a mistake. Also, you say it's WASD, but W and S do nothing.