Aarbron, a young boy, was kidnapped and enslaved by the Priests of the Beast Lord. He grew up on drugs that destroyed his will and turned him into the Beast Messenger, a powerful creature serving Maletoth, The Beast Lord himself. As he carried out his job, Aarbron began to notice a man about to be sacrificed in a ritual, whose face triggered ancient memories. Recognizing his father's face as the sacrificial knife descended, Aarbron remembered his childhood and the tormented past inflicted by the Beast Lord. He swore revenge and fled the temple, knowing the road to avenging his father and finding redemption would be hard.
Shadow of the Beast is a side-scrolling platformer with side-shooter elements. The player must navigate through several areas filled with enemies and traps, collecting keys and activating triggers that open new areas or give Aarbron the means to overcome sub-bosses. The player's moves are limited: duck, jump, and two attacks - punch and flying kick. While most enemies die with just one hit, the player must time each attack accurately. However, there are also traps of objects that cannot be destroyed, requiring the player to jump, duck, or move according to a sequence. The player has only one life with 12 hit points that can be replenished by collecting hidden objects in the level.