Paper Mario: The Thousand-Year Door

A thousand years ago there was a city. One day the city was buried. Another city was built on top, and all that remains of the previous city is a door. This is where the title "the thousand-year door" comes from. It's not known what could be behind this door, but everyone has different theories. Princess Peach finds a map and mails the map and a letter stating that Mario must come. So Mario comes to place called Rogueport where Peach was last seen. There he meets a female goomba named Goombella...