Version 2.2 of HoDoKu is now available at
Sourceforge. It contains lots of bug fixes and a few new UI features e.g.:
ColorKu mode (play with colors instead of digits)
Adjustable font size for the whole program (including menus and dialogs) - especially useful for visually impaired users or for large monitors
Write/read sudokus in several text file formats - including SimpleSudokus ss files
Improved mouse handling - playing using the mouse should be much smoother now, especially with alternate mouse mode
More options to control the display of the sudoku
The user manual has been updated to reflect all changes.
I got many complaints, that the gap between "hard" and "unfair" was too big, so I reduced the default maximum ratings for those two levels. This can have side effects when you use your own solver configurations.
Have fun!