Epic tip. try to form a "pocket" to sit in. Build walls really close on both sides of you and sit between them. you automatically rise up as the screen does, and zombies don't seem to recognize your vertical distance. so if they are "Close" to you, but above you on a platform, they will sit there swinging but can't actually hit you.
police officer: "cheif, there is a guy running around carrying a bomb!"
cheif:"forget him! we must catch the guy trying to escape after we randomly kidnapped him!"
for all the people thinking we got owned because say, 500 aliens got destroyed, and like, 600,000 pilots and crew got killed, not really. 500 alien SHIPS, and 600,000 PEOPLE. each shipped is obviously manned with more than one person. ;)
but anyways, i absolutely LOVED this game, favorited, 5/5, and i will be looking for a sequel... well done!