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don't you need to complete all the puzzles to complete the game??



Depends on what your definition of complete is? The Goal of this game was to finish it without getting Level 3 of Farming. This means that the puzzle #6 would never be completed, since Level 3 farming is needed to complete that particular puzzle.

It's the same thing with people who try to play without having a villager die on them. They will not complete the cemetary.