Das Geheimnis der Happy Hippo Insel (The Secret of Happy Hippo Island) is based on the Happy Hippo toy figures hidden in Kinder Überraschung chocolate eggs by Italian manufacturer Ferrero.
The game follows Max Mutig as he tries to uncover why the Volcano on Happy Hippo Island has started erupting again. Along the way, he meets his hippo friends who teach him new skills like climbing, diving, and throwing nuts at dangerous animals.
The gameplay involves exploring six areas with three levels each. Completing a level allows you to progress to the next one, with no save feature available. Instead, you receive a password that lets you resume play from where you left off.