What items must Mario collect in Super Paper Mario to undo the destruction?

In Super Paper Mario, Mario and his allies must collect the Pure Hearts to undo the destruction threatening the universe.

Count Bleck uses the Chaos Heart to open the Void, an expanding interdimensional rift intended to destroy the flawed universe. Merlon sends Mario on a quest to recover eight Pure Hearts, ancient objects whose power can counter the Chaos Heart and make it possible to confront Bleck.

The Pure Hearts are obtained across the game’s worlds and are usually connected to the resolution of each world’s central conflict. They also unlock progress through the dimensional doors leading from Flipside and Flopside. Once all eight have been gathered, the heroes can challenge Castle Bleck.

The main confusion is with the Crystal Stars, which belong to The Thousand-Year Door, and the Royal Stickers, which belong to Sticker Star. Super Paper Mario also differs mechanically from earlier entries: it is primarily a platform game with action-RPG elements, and its combat takes place in real time rather than through traditional turn-based battles.