HaniDoku is another sudoku variation.
More Information and a daily puzzle are on
sudoku - kakuro - hitori - hashi - slitherlink - battleship - pic-a-pix - link-a-pix - fill-a-pix - maze-a-pix - dot-a-pix - tents - centriko - hexa-trex - squaro - futoshiki - trigon - trizm - kenken - kendoku .................