Maybe I am a bit too strict when I say I didn't have an "aha" moment. There is still like level 7 where I thought "wait, is it possible that..." and it worked! Or when I found the ? using the ! I found before... And when I found the ! also, finding a strange behaviour that hint at what is special, trying it and it worked. I don't know if it can be more intense, but it was effective already :)