hard mode is tricky, but possible to complete. like some kind of puzzle, you need to think while placing units. someone has beat 16th day in survival, judging by highscores. wonder how :)
nice incarnation of plans vs zombies mechanics, with interesting features. great graphics, atmospheric music. everyone, who says it's too easy - welcome to hard mode, it's quite difficult. or survive till 16th day in survival, as did I :) 5/5