The idea is great, not just the Ninjas but the different colors that let you perform different actions. The fact that they all look alike doesn't bother much, or that there's actually no stealth involved even though they are ninjas (some kind of hide-in-the-shadows-and-wait-while-foes-past finesse would've been pretty neat). The levels are varied and fun, though I imagine you'd have to play a large amount of times to actually complete the game without a single death. It's a challenge. I like the background animation, the way the weather livens up each level, and the enemies are never still (on some checkpoints you start with one just beside you though, would be nice if checkpoints were safe zones). Keep it going!