A great idea, well executed.
As the levels vary a fair bit, I've commented on them 1 by one.
1 - At first I thought the music button was the thing out of place! Hehe... I see it now... but maybe the first level of the game could have been easier? (I think you should maybe have a couple of almost obvious levels to help us get into the game.
2 - got this one after examing everything for a few seconds. :)
3 - got it straight away. :D
4 - eh? How's that circle different? I had to guess, and even now, looking at it again, I still don't understand how it's different...
5 - rather easy. Got it straight away. Although I like that fact. ;)
6 - I actually thought it was the one above... Hmm... I'm not entirely sure why this one is either...
7 - easy if you know it. This one's just a test of knowledge.
8 - Fault - the button doesn't work until you click on 'hint'. I liked this level.
9 - I worked it out with the hint in your comments. The button's maybe a bit too small though? It should really stretch all the way across the screen, surely? Also, you can't press the button until you click to see the hint.
10 - Haven't got a clue. I couldn't even find the place by clicking about. I needed to right-click forward. (I think the left-most dot's supposed to be the button though...)
11 - Well, I got it, but I don't know why it's different and can't work it out...
12 - I liked this one. I might not have thought to zoom in had you not suggested it... Maybe a hint would have been nice?
13 - I just couldn't get this. I don't have a scoob and couldn't find the button by clicking about either. (I think it's spelled coincidence, but the 'e' wasn't a button...)
14 - The hint made this pretty easy. Without the hint, I don't think anyone would be able to know for sure where the button is.
I also like the way the game 'carries' on after that... (I only noticed it on my 2nd go round.)I'll maybe have to have a look at your pedestrian-killing game when it's released.
Overall, it's a well-made game and I applaud you.
I think you have just about the right number of levels, but I'm left a bit annoyed with the ones I didn't have a scoob about. Maybe you could add a control panel at the side in the next game? It could have a button for a hint (when available), music on/off buttons and a button that lets you skip the level if you can't work it out.
Then, at the end, you could maybe have an option to see why the answers were what they were?
I'd really like to know the thinking behind 4, 6, 10, 11 and 13.
The music was rather short and got annoying quickly. I don't think that's only because of the length - maybe the music could have been better chosen? Meh... it's good enough anyway.
It's a good game. I'd like to see another one, with buttons to skip past levels if you can't work it out and buttons at the end to either restart or go to an answers page. That's be even better.