its a solid game, great concept and execution.
a few suggestions for improvements maybe, no chainsaw or killing sound? its all drowned in that theme, which is good dont get me wrong but there is nothing more satisfying than hear that ironic chainsaw sound.
there could be more levels with obstacles? ie a street with over turned cars or a building with windows or pits etc
depending on where you want to go - over the top, you could have an announcer narrative the combo kills or how much life you have left etc - could give a indication of a story? why is he defending that one particular place night after night?
comedy - you could have a cleaner or random npc come in and try to clean the blood everynight and gets annoyed at the constant killing and storms off. squealing pig noises when an enemy dies, a reference to chainsaw massacre?
the difficulty is great and its gets hard fast, even on easy.
great work dude! :-)