First of all, I'm glad to see a new Riddle School game. Riddle School is my favourite game series.
This was overall, quite a good game. Smiley looked unusual though, I'm not used to seeing him with hair, he's usually got no hair like all the main characters, but I suppose you've decided to edit their appearances. I do prefer the original smiley, though.
The plot was quite good, and the things that Phil said were amusing. I thought it was hilarious when Nit-Wit poured soap in his eyes. I think it was good that Quiz became good, but I don't really like the idea of Diz becoming bad. Still, it was okay. I liked the flashback part where you had to go back to Riddle School 1.
I'm giving a 5/5, 10/10 rating for this game, because I like Riddle School and I'm glad there is a new game.