The game's story revolves around the Crests, six magical stones which preside over their respective elements (Fire, Earth, Water, Air, Time and Heaven). It is said that when all crests are combined, the Crest of Infinity will appear, allowing its holder infinite power and the ability to conquer all realms with it. The demons of the Demon Realm have long fought each other for possession of the Crests, five of which have since fallen into the hands of a red demon named Firebrand. Seeking infinite power, Firebrand challenges a Demon Dragon for the Crest of Heaven and is victorious. When he leaves to heal his wounds, however, the weakened Firebrand is attacked by a rival demon named Phalanx and loses all the Crests to him.
As the game begins, Phalanx has already begun using the Crests to become the ruler of the Demon Realm, while Firebrand is imprisoned in a coliseum and made to fight a zombified dragon. After escaping the coliseum, Firebrand sets out to regain the Crests and get revenge on Phalanx. Along the way, Firebrand is repeatedly challenged by Phalanx's general, Arma, who grudgingly returns each of the Crests to Firebrand out of respect for his power.
Finally, Firebrand challenges Phalanx in his castle within the Demon Realm. Depending on the player's choices, three different endings are possible in this battle. The worst ending has Firebrand killing Phalanx and leaving the Demon Realm to tear itself apart without a ruler, while a more favorable ending has a defeated Phalanx sealing himself inside the Crest of Heaven while Firebrand hides all the Crests. The true ending concludes with Firebrand slaying Phalanx after he uses the Crest of Heaven to transform into a hideous beast, then tossing the Crests off a cliff after deciding that he does not seek conquest.
Completing the game with the true ending gives the player a special password that allows Firebrand to continue the game with a new transformation, the Ultimate Gargoyle, which allows him to challenge a secret boss named Dark Demon. Upon winning this battle, a new ending plays in which Firebrand casts away the Crests out of pride for his own power, then leaves to seek another worthy opponent to fight.
The gameplay is a mix of standard platforming, with mild RPG elements. The stages are divived into six main areas and can be played multiple times. Often, the player has to revisit a level with new Crests to access areas, items, and bosses that could not be accessed before.
Firebrand's main abilities are his fire breath, claws for clinging onto walls, and wings to hover in the air (though he cannot gain height). As he collects Crests, Firebrand can transform and gain new powers that are specialized for combat and exploration: Ground Gargoyle, Aerial Gargoyle, Tidal Gargoyle, Legendary Gargoyle, and Ultimate Gargoyle. Other items to collect include extra hit points, flasks and spell vellums for using consumable magic items, and talismans that can improve Firebrand's abilities.