The forth installment from the highly popular Rhem series of games, Rhem 4 reveals another yet unknown part of the mysterious island of Rhem. The story continues where Rhem 3: The Secret Library ended, but the game can also be played independently of the Rhem Trilogy.

At the start of the game you are given the black crystal, which you discovered in The Secret Library by Zetais. With this crystal you can unlock the gateway to the unknown part of the island. Once again sense of adventure, logic, attentiveness and the ability to solve problems will help the player to slowly but surely unveil the mystery of this new adventure on this yet unknown part of Rhem. The existence of a secret transport system allows Kales for the first time to search for an exit from Rhem.

You will have to collect several parts of a key to allow you access to that transport system. Once again you are on your own to explore this huge, fantastic world full of strange vehicles and buildings, unknown mechanisms and machines, secret passages and doorways. You will meet new characters, that may help you solve some of the mysteries you will have to face.

Everything is part of one big enigma, and your task is to find the answers one by one.