• The griddle has a new puzzle this week called a “Funky Kakuro.”  It’s a kakuro with a couple extra twists.  All of the squares that will have an even number in them are marked with an “E” and other squares, with circles in them all contain the same number.
• Bozzball’s Puzzling World relaunched this week and a lot of new puzzles of various kinds were added including sipralgalzies, akari, and slants along with the traditional favorites.

At the KrazyDad blog, thousands of printable puzzles have been made available for free. The puzzles are sudoku and kakuro variations. They include what he calls jigoku puzzles, which are sometimes called greater-than sudokus and krypto kakuro puzzles where letters are substituted for the kakuro numbers.

Puzzle creator Cihan Atkay wrote two puzzles that appeared in this year’s Google US Puzzle Championship test.  On his blog, he’s posted four puzzles that were not included and they’re pretty interesting.

• Folding Sudoku - I’m not surprised that this wasn’t included since it requires solvers to cut the grid out of the paper and fold it.  (Scissors are not on the USPC allowed list.)  Still, it’s a very original sudoku variation.  I’m not sure that I entirely get it, though.
• Numberless Kakuro - Digits are replaced with letters.
• Cardboard - Requires you to fit abbreviations of former WPC hosts into a grid.  Puzzles like this show up in Atkay’s PQRST newsletter.
• Loop Lengths - Draw a single closed loop on a grid.  The loop must enclose the letters required to spell the loops length.

I came across this post about a puzzle called han’en that claims to combine elements of sudoku and kakuro.  Currently, the blog that this post comes from is dedicated entirely to the puzzle.

The puzzle is made up of a six by six with some numbers filled in.  At the end of each row and column is the sum for that row or column.  Each digit may only appear four times so that all of the numbers in the grid add up to 180 and this is where the puzzle get’s it’s name.  Han’en is Japanese for semicircle, and a semicircular arc has 180 degrees.  All of the normal kakuro rules apply.  No digit can be used twice in the same sum.  Only the digits 1-9 can be used. Essentially, it’s a 6X6 square kakuro with the added rule that each digit must be used only four times.  There’s also a variation called perfect han’en in which each row and column sums to 30.

I was at a book store Friday night and noticed a few kakuro books nestled into a display of sudoku related books. It looks like publishers are thinking that the current popularity of sudoku can help them sell book about another puzzle with a Japanese name.

Of course, kakuro (or cross-sum) puzzles aren’t new, but the buzz about them in the US has only risen very recently. Major web sites related to kakuro have shown up in the past six months, and it’s not hard to find blogs that discuss the puzzles and how to solve them.

I’ve often heard sudoku called a number crossword, which seemd odd too me since a sudoku is nothing like a crossword. There are, however, many similarites between crosswords and kakuro. A kakuro grid more closely resembles an American crossword grid. In a crossword, you are given a clue and the answer is limitted by how many blocks are available and by intersecting answers. Likewise with kakuro, you must find digits that sum to a specific value but you are limitted by the number of spaces and the intersecting sums. Additionally, no sum can contain the same digit twice.

It’ll be interesting to see if kakuro can become as big as sudoku and, if it does, what other kinds of puzzles will become popular after it.

Image from wikipedia.