City Underwater. Wimmelbuch

Nudibranchs are real aliens (although boring adults call them sea slugs). The planet Nudimon was destroyed. When the nudibranchs flew over Earth, their ship crashed and fell into the sea. Finding themselves underwater, our heroes built a whole city – Nudiland – and now invite us to dive in and enjoy adventures and puzzles.

In German, wimmelbuch means "book with bustling pictures". It has minimal text. However, the illustrations are bright, juicy, and full of details, characters, and events – they can be examined for hours.