Zigzagrams is an exciting evolution of Sudoku where players can construct elementary theories by applying a general rule that "every compartment must contain an odd number of odd numbers." The game is a rediscovery of the 9x9 square where a new logical dimension has been added to complement systematic search with imaginative thinking. By providing balance between discipline and creativity, Zigzagrams allows beginners to focus their search for the next entry while it empowers trained players with an enhanced set of "tricks" to combine. Each step of every puzzle in the collection can be solved...