I think there's a bug. If you completely fill a row/column with X's and Blocks then, if it's correct all the little numbers of that row/column get grey'd out, if there are errors in that row the numbers are grey'd out only partially. That way you can basically solve every riddle row by row...
Strange, how the game felt pretty challenging while it really was not. I didn't fail once in the campaign and my first try at survival ended after 14 minutes - long after unlocking the hard badge. But nvm... pays off in the high average rating!^^
Just lovely with the polished details and great gameplay.
Is it the flixel/pixel graphics that prevented it from receiving the 4+ avg score it deserves?