Great start! Issues: repetitious. too long to upgrade because the enemy on level 4 (with lazers, three shots to kill) gives the same money as level 1 (easy one shot kills).
Need way to skip intro, and when I am running to the side, I have to be all the way against the side. Also, when I have one ninja left, I can run forever and never find him. I guess it's OK, since it is just a advertisement game, but not good for a real game