Henry Sudoku
Hi, I am a sudoku addict from distant Singapore.
I hope you don't mind me using the forum to introduce some of my sudoku creations to your fellow countrymen.
My sudoku creation for this month (November 2008) in http://nrich.maths.org/public/viewer.php?rss=1&obj_id=6311&part=index is called the "LCM Sudoku".
For the first time, NRICH uses the creative and innovative idea of flash interactivity for its puzzles.
My first version of "LCM Sudoku" in an earlier issue of NRICH in the link http://nrich.maths.org/public/viewer.php?obj_id=6018 used unknown variables and numbers.
To be more specific, that variant should be called "Algebraic LCM Sudoku".
A more challenging version of my creation (LCM Sudoku) has been posted this month (November 2008) on the site http://www.chinasudoku.com/
Thank you for your comment. You are also welcome to comment on my "Colour Islands Sudoku" in http://nrich.maths.org/public/viewer.php?obj_id=6179
It is based upon part of the rules of my two board games, "Henry's Houses" and "Pseudo-GO", which are sold by Kadon Enterprises, Inc., online store.
As in a standard Sudoku, the object of the puzzle is to fill in the whole 9x9 grid with numbers 1 through 9 so that each row, each column, and each of the nine 3x3 boxes must contain all the nine different numbers 1 through 9.
There are coloured areas or "islands" in the 9x9 grid. Within each "island" there is an extra rule to apply:
Within each "island", every group of nine cells which form a 3x3 square must contain numbers 1 through 9.
those were really nice puzzles... 
My sudoku creation for the December 2008 NRICH http://nrich.maths.org/public/viewer.php?obj_id=6368 is named "Bochap Sudoku" which combines all four arithmetic operations to obtain the solution.
