Back in 2006, only a few sudoku variants such as the Killer Sudoku and Skyscraper Sudoku had been invented.
I can consider myself as the pioneer in the invention of sudoku variants outside Japan. After creating sudoku variants for NRICH and other websites for 3 years, it is time now to look back at what I have invented and achieved since 2006.
My first LCM Sudoku variant was invented in April 2008 as shown in
http://nrich.maths.org/public/viewer.php?obj_id=6018 A more difficult version of LCM Sudoku was invented in November 2008 as shown in
http://www.chinasudoku.com/A popular sudoku variant invented by me in November 2006 is the Twin Corresponding Sudoku as shown in
http://nrich.maths.org/public/viewer.php?obj_id=5477 I also designed it for the Second World Sudoku Championship 2007 at Prague.