Cardboard Confrontation
I liked the art, and I certainly appreciate the time and effort you put into it.
Still, there were some flaws that kept me from being able to really enjoy all of this as a whole.
The animation was suited to the "cardboard" theme and premise.
The music was unique and went nicely with the animation.
The only real thing that didn't seem to help was the rather lackluster story. As far as "havoc" goes there really wasn't much...and the robot leaves shortly after having arrived. The helicopter's really didn't serve much as of a purpose either, except as the one thing that gets destroyed by the unfortunate person being thrown by the robot.
As a short animation, this isn't bad at all. It seems you weren't planning a large scale "robot vs. city" thing here, and that's alright. If you were ever to expand on this I'd recommend drawing some more people, and maybe making the robot attack/be attacked a bit more.
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Good luck with your future animations! =D