Some of them can be easily solved, but many of them are pretty hard. The only hint you get is a little short message on bottom right corner. It tells the category of the riddle. The riddles’ answers can be a well-known books, songs, movies, children’s stories and bands.
Hint: If you are scratching your head now and desperate to solve all the riddles, you can hover your mouse on top of the image, the answer is in the tooltip.