Made it to the end with 16 deaths. I had a fun time the whole way through. I like that the death counter went up, instead of having a traditional lives/game over set up. I thought it was a great length for what it was. I particularly enjoyed how you introduced to players the knowledge that they could jump in mid air, simply by introducing a level that implied it could happen. I really appreciate when design is conveyed with no words, just gameplay :)
Also last note... that button sound effect is delicious!