SudoContest - Win prizes with the coolest Sudoku puzzles. You can join and play for free. At the end of each month prizes are available for the best players. The prices are paid by our advertisers. More info, see www.sudocontest.com.
SudoContest requires internet access to keep track of your puzzle performance and to download new puzzles.
SudoContest is completely free. First time you have to register but also that is free.