CheatCodes.com has all the official Impossible Creatures PC cheats to unlock everything. If you know of any that we don't have, please let us know.
All published and official codes as of Wednesday May 22, 2013 for Impossible Creatures are shown below.
To get the ultimate defense put up one row of upgraded bramble fence, then behind that 2 rows of upgraded sound beam towers, and finally behind that, one row of upgraded anti-air towers. You don't have to upgrade everything but I did and it was much stronger.
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