Reksio: Miasto Sekretów is the very first version of the game known worldwide as City of Secrets. This release was made only in Poland, Romania and Russia. In this edition players may experience elements removed in later versions, such as references to the first game series "Rex's Adventures", labyrinth mini-games, and the soundtrack derived from the first series.

Rex the Brave Dog goes down for a moment to the basement in the den of his friend Moles the Mole and literally "the ground swallows him up". The worried commander immediately sets off on his trail and soon, through a labyrinth of corridors and tunnels, he reaches an underground secret city of moles. It turns out that Rex has been captured, imprisoned and sentenced for spying for the Rats, and this, as it soon turns out, is just the tip of the iceberg.