Under rating threshold (hideshow)
Your Nurikabe is broken. There should be a move limiter to disallow cheating. IE fill the matrix and check solution. My average time with a 12 x 12 on paper is about 5 minutes, 3 with a 10 x 10. Given the direct notice of your "error gen", one could finish any of the 10 x 10 "puzzles" in well under 30 seconds.