What a cool game! I had a lot of fun playing this. It was almost immediately obvious what I had to do, and once that was done, I was having a blast doing all the intricate jumps from side to side. Also the ambience, sound design was fun.
My only criticism, really, is that it was a bit too easy. I didn't die once. And a couple of times I feel the dangerous objects were a bit too close to me, and I should have suffered damage.
Maybe if the ninja was a bit slower, and the colliders a bit wider (just a little in both cases), this would be more of a challenge. Congrats!