Pretty sure there are some error checking problems with this. Only been playing for about 5 to 10 minutes and played about 3 levels or so, and on 2 of the occasions the completed boards have had "3 errors". Obviously enough I go through them to check if there are any problems, bu each row, column and set was within the rules.
So, Idk, there's a chance I did make a mistake in them, but seriously, checking through I noticed no actual errors.
Otherwise, yeah, as some other people are saying - It's just Sudoku, try to put a twist on it or something.