Paper Mario: The Thousand-Year Door is a videogame for the Nintendo GameCube and the true sequel to Paper Mario for the Nintendo 64. The game uses the same battle engine as its predecessor, but it also has a few changes. These range from Partner Hit Points to the Audience system.
The game takes place in the dangerous world of Rogueport where the Princess has found a strange map. She mails it to Mario who sets sail for the country. Almost immediately strange things begin to happen. A young goomba is being attacked by a group of thugs, and Mario steps in to save the day! Of course, Mario and his new friend go to see a professor who investigates the map, and discovers it's connected to a secret door named The Thousand Year Door! Behind the door, however, is a mystery. Soon, Mario will unlock this mystery, which will unlock one thousand years of mystery...