Not bad
Well illustrated and enjoyable. As you said, it was rather unchallenging, unless you actually work as fast as you can which I began doing towards the end.
However, I don't think it's such a great idea to make that the only challenge, for example the "memory" game with the waves washing away the objects was simply too easy, even when working as fast as possible.
Thus, in that game you have 2 possible factors to measure IQ, the quantity of objects, and the timeing of the player.
The castle matching and first look games were fine, I found myself taking slightly longer each time as the timer progressed.