Hey, that was a good and neat idea. My only problem seemed to be that the UI took up so much screen real estate -- it was nice that you allowed the player to hide it, but it was so essential I didn't really want to do that either. I get the whole appeal of using the whole keyboard, but maybe you could confine it to just the qweasdzxc keys or something so both the UI takes up less space and also so the player doesn't have to stretch their hand strangely across the keyboard?
But hey, fun game, good difficulty curve. I like how the player has two ways to solve a level -- get better at planning and thinking when to use the buttons, or get better at execution of the plan.