I suck at the classic puzzle, so I'm impressed that I even made it past level one. I did get stuck on the third level, at which point there was so many variables that my tiny little brain caved in. The complexity of the puzzles increased at an exponential rate, it probably would have been nice to have a few more intermediate levels to develop strategies with each of the animals. That was quite an interesting puzzle, but I still think it would be easier if the animals just vaulted the fence =)