Two achievements don't work
Nice game, similar feel to D-Day Defender. Only thing I see wrong with it is that there aren't any explosions, so you can't get the "Light My Fire" achievement, and I've killed dozens of people with boiling oil (including one wave where I killed 10 people at once with it) and didn't get that one either.
Also there's no good reason you shouldn't be able to keep playing forever once you get the hang of it. I'm not sure whether that's a good thing or a bad thing.