Berks

The reason the Berks became angry and attacked before being destroyed was because someone infiltrated their city and stole their treasure, the source of their powers. You take control of the person responsible as you move around the flick-screen maze in your Terror Tank collecting keys to get deeper into the city. Your first task is to collect 21 keys to enter the Inner Sanctum, then collect four keys to enter the Heart of the Inner Sanctum, before you have to collect ten keys to enter the Sacred Treasure Chamber. The keys are protected by protective blocks and these need blasting to remove them. As you explore the city you will encounter Berks and Drones, the Berks can be destroyed with your laser but the Drones can only be stunned. If you touch a Berk, Drone or a protective block then you lose one of five lives. There are five skill levels to choose from and they are Duffer, Novice, Normal, Expert and Master.

Despite the name on the box, this is actually a conversion of the Plus/4 game Berks III, but since the first two games were never released on the Amstrad, it was named Berks on the box, which is why the title screen actually says Berks III.