Freezing enemies as a means of non-lethal takedown is a pretty neat take on the theme, though the zombie elves sticking around once frozen meant that once I formed a barricade of ice-cubes it became a waiting game towards an inevitable victory. That's fine though, barricading yourself in is a time-honored strategy of zombie games :]
As a side note, if you're going to make a sound play once per second for the duration of the whole game, it really could do with a little bit of variety.