After playing the game for a while, I found a 'Zoo Keeper' badge; it gives +300% XP for the first-time completion of animal puzzles. For anyone going after Kongregate's hard badge, this will save you a lot of time. I think I got it after completing enough animal puzzles, but I don't know for sure. If that is the case, I recommend completing enough easy puzzles to get the Zoo Keeper badge and then doing normal levels for bonus XP, but again I don't know exactly why I got that badge (I got it after doing an easy animal puzzle, but I had already done some normal ones too).
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