Mario and company are enjoying the outdoors when a mysterious cloud forms in the distance. As the cloud moves closer, a giant bag appears to be floating in its midst. The bag opens up to reveal the giant Party Cube! Out comes Toad, Goomba, Boo, Shy Guy, and Koopa and invites you to yet another party.
It’s your birthday! Each host is ready to celebrate the big day by each giving you a present! Before the presents can be handed out, each host will have you play in their board. If you win, that host will challenge you to a mini-game and winning will get you the prize.
Goomba’s Greedy Gala
Shy Guy’s Jungle Jam
Toad’s Midway Madness
Boo’s Haunted Bash
Koopa’s Seaside Soiree
With every board complete and each present given, Bowser shows up and threatens to take all of the presents and sets up a board of his own. Without thought, the player accpets Bowser’s challenge and heads over to Bowser’s Gnarly Party for the final board game.
After placing first in Bowser’s board, Koopa Kid will congratulate you on winning. However, Bowser is able to trick the player into going into The Final Battle!, a mini-game of his own. Bowser promises the presents, as long as the player can get to him.
Once the player goes through the entire level and defeats Bowser himself, Bowser will give up and run away, leaving a small present behind. Koopa Kid will then drop by and explain that Bowser never took the presents in the first place and that he may just be a good guy. The present is then opened and the gift from Bowser is received.
Bowser is later seen walking away with mixed feelings regarding your birthday. Toad appears and explains that there is still someone left who hasn’t given their gift yet. Toad points to the sky to reveal a Star, that zips around the sky revealing a constellation of the character of their winning pose.
As the credits roll, some of the background of the Party Cube is revealed. The five hosts are seen approaching the mysterious Party Cube coming out of a warp pipe. They proceed to inscribe themselves over the cube and soon find an evelope full of invitations. They send Lakitu out with an evelope to send them to the Mario and the rest of the crew. The hosts find costumes and the Star appears as the Party Cube begins to move.
The epilogue shows the hosts, without their costumes, following after the moving Party cube. After a few seconds, the Party Cube blasts off into space, never to be seen again.