it is very hard, but is really unfair? the real Ninja does follows the law of reflection, where the reflection angle is equal to the incidence angle with the surface normal, like this Image
given this new info, I would love if you were to give it another shot ;) my highest score so far is 31.
the game is intended to have multiple levels each with it's own speed difficulty, since there are so many beautiful level design ideas, but due to limited time we decided it's best to make an endless level with increasing speed as a linear function of score.
and I'm really glad you enjoyed it :)