Not Perfect but...
it was a good try to make it perfect...it's just way too easy after you get second level weapons that cost over 2000...I quit after I got bored just spraying my weapon and not getting hit multiple times but it's still a good game for a sequel...
-Balance the weapons, some cost the same but one is better than the other...
-Give the zombies a little HP as the levels go on so it's something different every lvl
-more upgrades like mines, barbed wires, electric fences, mud to slow them down
-explosives like grenades and rockets launchers...
overall good job, it's one of my favorite games...