Dude, that ending, it almost made me cry, my eyes are almost about to do it, but I don't know why! I have never cried from a flash game, you have done an excellent job in gameplay and stoyryline! 5/5 :)
For people having trouble with the super boss mode at wave 30, try to keep your HP as max as possible, and first take down the mortar, then the axeman, those are the biggest threats, the shield is nothing but waiting until he takes his gun out and shoot you, I won the game that way :)