This is probably the best damn zombie game ever (Yes, I have played Dead Rising 1 & 2, Resident Evil, and lots of flash games here. This is exactly what I think when I think "Zombie Apocalypse")
A decent start, I hope you keep working on it as it has some potential (since BM2 was never finished, try working on the late game stuff before you keep working on the whole "total conversion mod" aspect)
Have to agree with "DarkLordKhaos" here. This game isn't "challenging" so much as it is one of the many (horrible) "how many pixels can you comb over" games. Who the heck found the "hook" without combing pixels?!