Arrow keys to move, space to throw a ninja star (if you have any), if you touch the right edge of the screen you will go to the next level. The grey words at the top will give you more information. Since the skeleton's eyes are black, there is a 0.34% chance that if you are holding there up arrow and the left/right arrow you will wall jump off the skeleton. Also on the boss level you get unlimited ninja stars.
Original Platformer: https://scratch.mit.edu/projects/292625833/ Level 28 is possible. You can't wall jump on the boss level. Thanks to @atomicmagicnumber for the numbers Thanks to @Wil_Wam for boss fight music.
