Excellent work you've done here!
Okay, I'll admit it. It isn't nearly as hard as it should or could be, but when you die it is your own fault for ... you know, dying. The star off is actually because spike blocks instantly kill you no matter where you come at them from, and the art should reflect that. Also you cannot jump without double-jumping first, and there are ways of showing this in the earlier levels, even without explicit text mentioning this.
Still, the fact is (when you grasp the concept) once you die, it's your fault, and that's what makes a good hard game in my opinion. I am interested in seeing what new levels you come up with.
Wait, is this... GLITCH LAB 2!?
Ok, i liked this game so... I'm witing here!
First the character is easy to control, no slicing or else, it's very precise (it deserves well the game's objectives)
The fact that when you "fall" you ca'nt use your double jump to jump once (like 99% of other platformers) is quite disturbing but not so important.
The moving spike blocs should have spikes all around them, because when I found one I thought only the bottom (spikes) would have kill me, not the top (which have same sprites than floor).
Btw, the "Impossible-Game" near the name made me play at it, but It's far overrated... It took me like 5min to achieve it.
You could expand the playing time of your game (after it's completion) with adding in-game timer, and a leaderboard, made for a "hardcore player" which could see his best timer for each lvl, and want to improve it till a great score ! (CrateRun is one of the best kinds of it, or just MeatBoy)
Eh... I'm talking too much :D Improve the difficulty, add a timer, add levels, and it will be great !