I liked the game! Working on gamepad was a big plus for me. I have some suggestions to spice up the game a little bit. You don't need to take them seriously, they are just ideas that crossed my mind while playing:
- The shurikens could be faster! Also, the color of the shurikens should be very distinct. The enemy's shuriken could be very different from the player's in hue. In fact, I wouldn't mind if they were pink, blue or red!
- How about a melee attack as well for the ninja? That would be very cool!
- One way to make a variety of enemies by recycling resources is: change colors, sizes and speed;
- The waves could automatically start, without the need to press the red button. How about a timer? Then you could show a text in the screen showing the seconds: 5, 4, 3... 1 Go! Or something like that;
- I know its hard to make music, but there is a trick to make reasonably acceptable ones for fast-paced games. The secret is the beat! Put the tempo high and go crazy (maybe not so crazy) with the beats. Then it becomes easy to lay down some chords and put a melody on top (it can be a variation of the chords, with small changes);
Nice game, good job!