I have played through all of zone 1 using only the ice gun and I still do not have the achievement for it. I play on medium, I do not die and this damn achievement will not unlock... Can anyone tell me what it is I am doing wrong?
I would post this with my actual acct. but I do not post in the forums with it anymore.

Just to be clear, you finished the entire area?  You get it a bit before the wall you fight.

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Zombies everywhere, zombies everywhere, zombies everywhere. They're coming for your brains and it's too late to change.

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[)X Life Is Short - Play Naked X(]