The glitches were small at first. A misplaced texture, a disordinant chord, a wonky-looking goomba. Then, in the deep recesses of Bowser's kingdom, a small break formed. A deep midnight black rift in the sky, from which a dark cloud leaked out, enveloping a nearby koopa, turning its eyes red.
Mario, noticing the anomalies, went closer to investigate, and observed a chilling sight of a troop of koopas moving in unison, their eyes all red. Fleeing the scene, he went to Princess Peach to warn her of the enemy, thinking it to be another one of Bowser's tricks, and once he gets there he sees an army of toads, moving in the same unison, behind a black-cloud enveloped cloud, their normally cheerful noises replaced by rasps, figures distorting slightly on the edges, eyes pure red and full of malice. Mario runs away, mentally apologizing to Peach for not saving her from this fate. As he flees, he hears a voice in his head that sounds like his creator, telling him to seek out Bowser. Mario objects at first, but then realizes Bowser is a lot better at brute force than him, and listens.
In Bowser's kingdom, Bowser was seriously annoyed. Kamek had been giving him reports of koopa disobedience all day, with similar effects on most of his minions, from his boos to shy guys. He calls in his son, Bowser Jr, and asks him about it. Bowser Jr doesn't know anything, and then a small troop of Koopas comes in, attacking and throwing bob-ombs, blowing apart the throne room. Bowser just barely escapes in his clown car with his son, but a well-thrown Bob-omb knocks Bowser to the ground, yelling at his son to run. As Bowser turns around to face the army in front of him, he sees his castle overtaken by a malicious dark cloud, and Kamek flying away, unharmed. -or so he hopes. He breathes fire into the sky, a flaming protest against this corruption of his home. He is about to run into the fray when he hears a voice telling him to find Mario for help. He laughs cruelly, telling the voice he doesn't want to see his enemy, but the voice says if he doesn't he will be consumed by the darkness, the darkness feeding off of his natural chaos convinced him. He hated Mario, but he loved freedom more. So, fire shooting behind him, he went to mind his once-advasary, now his only hope.
Mario and Bowser, fighting through an endless horde of enemies, finally met up, led by The Voice. Mario, hopeful, offers a truce first, and Bowser accepts in the face of the endless horde. They face the enemy together, fighting back-to-back, covering each other's weak points. Following The Voice's lead they make their way through mountains, rivers, forests, and valleys to the most nostalgic part of the mushroom kingdom, the legendary level 1-1. There, at the very beginning of the level, they see a rift that isn't like the others. This one was a brilliant white instead of a midnight black, a light of rebirth, promise, and pure code and hope. The Voice tells them to go through, and they do, heading into the mystery beyond…