I thought the puzzles were well constructed and didn't notice the omission in the puzzle with the mistake.
My only problem with the contest was that the Odd/Even puzzle didn't allow for people solving online to input anything in the boxes around the 9x9 grid. Not being able to input these numbers turned a 11 point grid into a 30+ point grid in difficulty. If the people who printed out the puzzles don't understand where I'm coming from, try solving the puzzle blind-folded so that the puzzle becomes a test of your memory to solve a puzzle rather than a test of using logic.
Sorry to ask a bit late and probably not in the best topic, but I have a request. I solved Sudoku City online and found the 'Undo' button quite useful. Unfortunately I clicked on it too many times when solving the Product Sudoku and I got lost which correct numbers I have removed (I was too tired :( ).
Would it be possible to add a 'Redo' button as well or it would be an advantage for online solvers because offline solvers can't 'redo' erased numbers from the 'memory' of the paper?