One day, Mario, Luigi, Peach, Toad, and Yoshi were enjoying a picnic in the usual day of the Mushroom Kingdom. They ended the picnic and were about to head back home until they was a strange looking bar next to Toad Town. They were just going to leave it there, but their curiosity got the best of them and they decided to check it out. There they saw an old enemy of theirs; Mouser. They wanted to know what he was up to. He told them that he wasn't looking for trouble, but instead, for challengers for his 8 World Trial. They expected to be something like the normal adventures, they been throughout because nearly every main series 2D platforming game has at least 8worlds. They were mostly expecting an easy adventure for that reason. Unfortunately, thwy were far from wrong, for this quest is far mor harder than the previous journeys they had overcame. Now The Mario Bros., Peach and her guard, and Yoshi must beat the Eight Challenge Guardians before they can finish the Trial.