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A Challenging and Addictive Sodoku Variant.,
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This review is from: Tri-doku (Paperback)I have almost completely given up solving the plain vanilla 9X9 Sodoku puzzles, although I do still enjoy some of the variants. However, I now usually carry the some of the larger Kendoku puzzles (8X8 or 9X9) with me, especially for the convenience of something to occupy my time when I am traveling or know that I might be waiting somewhere. I find that Kendoku provides much more of a mental challenge and is much more enjoyable for me.
Recently, I was looking at some Amazon email offers and noticed this unique Sudoku variant. The creator, Japeth Light , seems to consistently construct high quality puzzles, so I decide to give these a try. In my opinion, they are great fun and the book is an extremely good value. A Tri-Doku puzzle consists of nine3x3x3 triangles with a base of 5 numbers, a middle row of 3 numbers and an apex (or base in the case of the three inverted triangles. Each inner triangle must contains the numbers 1-9. The nine small triangles form a large 9X9X9 triangle. Each of the three outside legs of the large triangle must also contain the numbers 1-9. There is also an inner shaded triangle with legs of nine cells each of which must also contain the numbers 1-9. Thus, some cells contain a number which is only used for the triangle which contains the cell, some cells are usued for two triangles, and three cells contain a number which is used for the triangle in which they are located, the larger outer triangle and the inner triangle.
The key is to understand the rules and the tips for solving the puzzles. No two cells which touch (even if they are in different triangles) may contain the same number, not only cells that share an edge but cells that just meet at a point. (Note that cells which share a horizontal or angled row can have numbers repeated if they are not adjacent, it took me a few puzzles to get used to this difference from Sudoku.) The key rule is THE HEXAGON RULE, which is well illustrated in the introduction but which it took me a while to assimilate into my puzzle solving techniques. The key tip is the strategy of utilizing POWER CELLS to eliminate 5 or 6 of the nine possible locations for the placement of a number in an adjacent triangle.
The book consists of 180 puzzles of increasing difficulty - easy, medium, hard and `monster". T- I have completed 46 of the puzzles including several in each category; the first three categories increase gradually in difficulty and a few of those rated medium seemed as difficult as some of those rated hard. However, I have found that all 6 monster puzzles which I have completed to be much more difficult and time consuming than the hard puzzles. All the puzzles which I have completed could be solved by means of logic, no guesses were needed. And in all cases there was only one correct solution possible; one of my major annoyances is when I near the completion of a sloppily constructed puzzle (probably often computer generated) and find out that there are alternative solutions because symmetrical cells can be flipped.
I wholeheartedly recommend this book for puzzle enthusiasts who like logic puzzles employing numerical solutions. I have become addicted and hope that eventually some more books with additional puzzles are created.
Tucker Andersen July 12, 2011