Good concept
Still needs a lot of work but has potential. The character movement is a bit on the slow side, if he's supposed to be a ninja then you should speed him up. Also it would be cool to see him have some alternate attacks or powerups (smoke, throwing stars, invisibility, whatever). Maybe make him able to hide in certain spots in the background too? i noticed that you dont die when you fall at the end of the level.... anwyays good job, finish it up and it could be awesome