I filled every square, but had errors. I received the "keep trying" alert. The alert was accurate, but it was annoying that as long as the puzzle was complete (every square filled) AND incorrect, I had to dismiss the alert every time to keep going. So if I just changed one square, and the puzzle continued to be filled but wrong, the alert showed up again. Perhaps using an inline error message rather than a modal would be less friction.

Also: when completed the puzzle correctly, I was told "Congratulations! You have completed the puzzle correctly in Om Os!" — which was much shorter than my actual time. :)