Mario crash lands in the Dark Chocolate dominion, little more than a stone’s throw away from Bowser Bastille. As he looks around the seemingly never-ending marsh looking for a way forward, he is struck by a flying bone and notices a familiar skull emerging from the depths of the foul-smelling bog.

After being acquainted with Bowser's dominion, Mario charges onward towards the looming castle but is soon faced with a large poison river obstructing his path! With no other choice, Mario is forced to get on the snake block lying ahead and ride down the river, knowing that his final destination is not much farther.

Many have entered this old house, but none have ever left. As Mario approaches the front door, he hears an ethereal voice whisper in his ear: "Welcome home."

Bowser's dominion has turned the forest into Toxic Trees! Mario must work his way through them, but he must tread carefully in the now infested treetops!

At last, Mario has almost reached his final challenge where Bowser will surely be laying in wait! Obstructing his path is an ancient citadel infested with spinies and munchers lead by an old foe. Unsteady ledges form precarious obstacles, but Mario can taste victory.

This is it: the final castle of the Dark Chocolate Dominion. Four doors appear before our heroes, one for each. Can they survive the Koopa terrors that wait for them on the other side? Will they be able to climb the lava tower and save Yoshi? Or will Bowser's cruel laughter echo through the dark skies? Go, heroes, and bring peace to the Mushroom Kingdom once more!