While it was not challenging SQL, it does require paying attention to the prompt, writing the queries, and following the clues. I could easily see myself blowing it in an interviewing situation with someone staring me down. In the zero pressure environment at home, I almost tripped on the fact that the license plate clue said it "included XYZ" while I initially queried `like 'XYZ%'`
I even use it for hiring exercises.