I'll admit that it seems that Kobo's Sudoku is making periodic mistakes to me as well, but it is very hard to prove. As much as I play "like a computer", I cannot deny that I am human. I cannot deny that I am failable. It doesn't take much to make a mistake after all. A misobservation, seeing something that isn't there or missing something that is there, is all too easy after all.

At the end of the day, the number of solutions that I've come up with that Kobo didn't agree with (and that seemed to be right nevertheless) are countable on the digits of one hand. So, for Sudoku, I'm happy. Chess is a different issue though. It has faltered when it shouldn't. That does disappoint me, since I would like to get into games deeper than Sudoku, Solitaire, and Boggle. (As added fun, they don't call the game boggle but the library does refer to Boggle.)