During my study Communication & Multimedia Design I and 3 other students made a travel website together with a viral animation where people could win prizes if they could find the hidden icons.
I designed the 2nd level
1st level: 1) click on the bird, 2) click on the dolphin, 3) click on the guy running in the background 4) repeatedly click on the coconut-tree.
2nd level : find out yourself :-)