Down in the center of the universe, the Millennium Star is born! A star that is only born once every thousand years will grant the holder of the star, to be deemed as the SuperStar of the Universe. Being a newborn star, the star quickly fell from the sky heading straight towards the Mushroom Kingdom.
At the same time, Mario is relaxing in front of the castle as he is nearly struck by the incoming Star! It’s not long before the Mario Party gang shows up to investigate. They soon start a feud over who should keep the Millennium Star when Lakitu flies by with an odd toy box. After dropping off the box, Mario and friends look inside to find a Mario Party sign along with a blue dice block. At that very moment the Millennium Star gave out a bright light transporting everyone into the toy box…
The outcome of the flash was not what the gang had expected. The entire Mushroom Kingdom was now two dimensional objects and paper thin structures. To everyone’s amazement, the blue dice block transformed into a living being that took no time wasting getting the gang over to the party boards.
With Mario Party in mind, the Millennium Star challenges the players to face each other off by collecting Star Stamps rewarded by winning Battle Royale Maps and Duel Maps. Collecting all seven will award you the title of SuperStar.
In order to earn each Star Stamp, you must play through the Star Stamp’s Battle Royale board. After winning first place, you are challenged by another character to a Duel Map board. Once that character is defeated, the Star Stamp is yours. In addition to that, each Stamp has a trait associated with it:
In the meantime…
The first stamp to collect is the Wit Star. It can be obtained once you beat all your opponents on the Battle Royale Map, Chilly Waters. Once the player wins, he/she is confronted by Wario who believes he deserves the Stamp. The Millennium Star decides to settle the dispute by starting up a game on the Duel Map, Gate Guy. If the player beats Wario, he/she will get the stamp and move onto the next Stamp. As soon as everyone leaves to play the next board, Bowser appears, but is too late.
The Kindness Stamp is given to the player when they beat Deep Blooper Sea. Yoshi challenges you to Arrowhead, but gives up the fight for the stamp when you come out on top in the Duel Board. Bowser appears, but once again, he arrives late.
The third stamp, the Strength Stamp, is awarded to the player after Spiny Desert is completed. Pipesqueak, the third Duel Board, will be played when DK challenges you for the Strength Stamp. After the duel, Bowser confronts you and the Millennium Star, but is surprised to see that they left after he performs his victory dance.
The Love Stamp is awarded to the player for beating Woody Woods. Before the Stamp is awarded, Peach bursts through the Castle doors and challenges you for the Love Stamp. The Millennium Star moves the duel to the Duel Map, Blowhard. After beating Peach, Bowser appears to stop you from advancing any further. Tumble kindly asks Bowser to move which he solemnly does letting you move to the next board.
For the Courage Stamp, you will have to play a match at Creepy Cavern. After the game, Mario will appear and challenge you for the Stamp. After a match on Mr. Mover, you are awarded the Courage Stamp and prepare to move onto the next board. Surprisingly, Daisy appears out of the order and demands the next stamp, the Beauty Stamp, be handed over to her. With the Millennium Star now in a daze, he begins to hand over the stamp when Tumble snaps out of it and has the Millennium Star agree to start a Duel Map on Backtrack. As they set off to start the match, they are confronted by Bowser once again, but this time Daisy is able to smack him clear across the castle.
After defeating Daisy and earning the Beauty Stamp, the Millennium Star begins to prepare the next board for the final Stamp, the Mischief Stamp. Bowser appears starting a argument that eventually ends in sending the Mischief Stamp flying into the castle. Once Tumble realizes that the stamp is missing, Waluigi appears at the castle with an imprisoned Mischief Stamp. Bowser, wanting the stamp for himself, begins a fight with Waluigi that ends with Bowser flat on the ground. Waluigi challenges you to a board game on Waluigi’s Island if he wants to get the stamp back. As you are leaving, a defeated Bowser tells you to avenge him and beat Waluigi.
With Waluigi defeated, the Millennium Star grants you the final stamp needed to become the SuperStar. Not long after your victory dance, the Millennium Star informs you that there is still one more character to battle. It is revealed that you must defeat the Millennium Star, shocking news to both you and Tumble. The Millennium Star takes you to the final mini-game, Stardust Battle.
With all the stamps collected and the Millennium Star defeated, you are now expecting to be named the SuperStar. The Millennium Star admits he has a confession to make. He is not in fact the Millennium Star. Once the Millennium Star flees, you are seen disappointed, finding out everything that was done was for nothing.
Just as things were at its lowest, Tumble begins to glow! The dice on his head opens up, revealing a small, white star who informs you that he is the true Millennium Star. He says he has been watching you the entire time and begins to transform the Mushroom Kingdom back to its original state. Before everything turns back to normal, the true Millennium Star lets you know that you will become the SuperStar. After the transformation, Mario, Luigi, Peach, Yoshi, Wario, DK, Daisy, and Waluigi are all seen relaxing and enjoying themselves back in the normal world.
After the credits, a final scene is shown where a die, the same seen on Tumble’s head, is seen being rolled onto a table that has a board game with the “Mario Party” title written on it. The words “End” are seen in the corner, signifying the end of the game’s Story Mode.