I love the colors, and the music really comes through. I hope you'll update the game after the gamejam so we can enjoy some more polish. Well done.

Good work on getting a game submitted in the 48 (+8) hours. The environment/level design was probably the best part of this game. I've left some constructive comments on the voting areas below:

Theme: You get points for the theme, very funny to have a rubber duck as a weapon. I would have LOVED the ability to throw the rubber duck as a projectile.
Creativity: The most creative element here was your level design, it was good to see a different colour scheme for each level.
Technical Achievement: Unfortunately this game was quite laggy for me despite having a halfway decent computer - I'm not sure why this would be. I found the camera frustrating to deal with, whenever enemies would get close to me the camera would move unnecessarily close to the player character. There was no consequence for me getting hit by the enemies? 
Polish: A few things could be tidied up - there was no 'end' to the game. I was just running around the island on the third level. Also, it would be good if you could implement player-out-of-bounds to this level because I was able to run into the ocean, underwater, and off the landscape into the abyss :) I also would have liked the drawbridge/wooden walls to fall, break, or be pushed away instead of just disappearing.
Entertainment: Enjoyable in the sense that I enjoy running around. The game could benefit from a story to push entertainment: why am I being attacked by zombies, why is my weapon a duck, why am I running through these colourful worlds :)

Bonus Points: I found it funny how one zombie ran into a box and then launched himself into the ocean as consequence. Probably an unintended result from you haha.

Cool idea, I liked the graphics and the goofy physics, the camera seems to zoom way too close sometimes and some levels dropped my FPS but other than that good job!