This was one difficult color test! As a designer I thought I'd be able to answer at least the Easy one without references, but no deal, even the Easy mode's hard, the Normal mode's harder and the Hard mode seems to be pretty much impossible considering no one's attained that medal yet.
I like the idea, but it'd be more fun to play if there weren't so many questions in each quiz, and maybe at least a small threshold of wrong answers you can have and still 'pass' a quiz? Maybe a limited set of 'Undos' you can use during each run through? Keep it going!
-cd-