I had a lot of fun with this one, played thru it twice. You make good use of the limited hazards, like where you have to jump between ninja stars to dodge oncoming bullets, real nice.
There’s two adjustments I would make to the hero’s jumping: 1, jumps shouldn’t re-trigger when you hit the ground again if you hold the button throughout. And 2, the jump ought to cut short when you release the button. Gives the player a bit more control.
The graphics are great, they read nice and clear, but if you spend more time on it, it would add a lot to animate the hero.