Wario World is a beat-em-up platformer starring the greedy antihero Wario, who has finally built himself a grand castle stuffed with all the treasure he has plundered over his many adventures. His contentment is short-lived. Hidden deep within his glittering hoard lies an evil, sentient gem known as the Black Jewel, which suddenly awakens and seizes control of the castle. With a surge of dark power, the Black Jewel corrupts Wario's beloved treasures, twisting them into monstrous enemies, and warps the castle itself into four sprawling worlds teeming with danger. Furious at the theft of his riches, Wario storms into these transformed realms to take back what is his. As he punches, piledrives, and hurls his way through hordes of foes, he also works to free the Spritelings, tiny creatures who long ago sealed the Black Jewel away, in his rampaging quest to reclaim both his fortune and his home.