Great game idea. I like the music and the controls. Not too hard and not too easy. I liked the ninja penguins in the ice stage but didn't like the underwater levels. I think you should only have levels in which you move side to side, adding a up and down makes things too hard.
Reviews for "Retro Ninja Star"
Should have been done with arrow keys.
The mouse doesn't really do anything but make it harder to control.