Let me invite you to try our new on-line training in solving sudoku variants (jigsaw, diagonal, windoku, etc.) for the HALAS league competition which will take place on sudokucup server on 18-21 May 2012 (2 rounds of sudoku and 2 rounds of puzzles - so more than 4 hours of solving!).
New puzzle every day!
http://sudokucup.com/node/1901
The schedule of sudoku variants for this week:
01.05.2012 - Jigsaw sudoku
02.05.2012 - Diagonal sudoku
03.05.2012 - Windoku
04.05.2012 - Jigsaw sudoku
05.05.2012 - Diagonal sudoku
06.05.2012 - Windoku

SUDOKU BOOK