I think it's pretty fun, and also some of the riddles are unique. However some of them could have been better like the bunny, city (A___M), and bird ones which basically just are looking up stuff on the internet. And the bunny one specifically tells you to use Wikipedia which gives you a different answer (Leporidae or something) than the correct answer.
I got stuck on last level. The hint said the answer was in the picture. Some observations: the tree is shaped kind of like a brain, and the wind is blowing everything to the right side (or left side from the tree's perspective). But I didn't get it. I also don't get why the hint says to "think Recalls", is the answer related to the word "recalls"? And is the "R" capitalized on purpose?
The best answer I thought of was "reminisce" since it has a similar meaning to "recall" and in the song John Lennon is "reminiscing" about what the world could be like. But it doesn't really make sense with the picture.