Had a blast playing this! Felt like a very smooth and challenging one-button version of Super Meat Boy! Definitely a very interesting approach to the game: I always enjoy seeing these minimal-input experiments and I felt this was a great example of them at their best. Level design was quite varied with lots of fun obstacles, and I loved the little touches to the game, such as the way the mole belly-flops on death: with a game as tough as this, it's good that even death is fun, haha!
My only complaint was that, as smooth as the game was in general, there were a few annoying parts where the time-freeze from collecting keys threw me off my jump timing, and sometimes the game would eat my jump inputs for some fast-paced jumps, requiring me to input way earlier than I expected. All in all, though, very solid job!
It's not necessary, but if you make some bonus levels for this, I'm down to play 'em because I really want more of this!