Thanks for the feedbacks guys!
@ urmelhelble : sounds like a bug... very odd. Did all your columns and rows have their hints greyed?
@ Nicotine_x : you're right, it was planned, but I got a little impatient. Might add it in a soon future though
@ datanoh : not necessarily. I mean, this is how I've designed the game ;) Some grids do have unique solutions, some don't. I couldn't see a good reason to punish people who did complete the grid by clearing all the hints, so you win as long as all the hints are greyed and there are no boxes left to place