Very cool take on this game genre! It was easy to control your character, the rate of fire felt good, the time it takes to reload was right on, as was the zombies' speed. The whole "toss down a piece of gold to distract them" mechanic was a nice touch.
There are two things I'd like to see in an update. Turn the music down a bit so I can hear the sound effects better, and work on the window sprites a bit. It took me a second to realize those were windows and that I could shoot through them.
Again, these are just nitpicky minor issues. Great job!