Paper Mario: The Thousand-Year Door is a role-playing video game developed by Intelligent Systems and published by Nintendo. Released in 2004 for the GameCube, The Thousand-Year Door is the second installment in the Paper Mario series.

Following in the footsteps of its predecessor, “Paper Mario” for the Nintendo 64, the game implements many of the same gameplay elements such as a paper-based art style and a turn-based battle system. The game expands upon the elements that the original Paper Mario excelled at while implementing new ideas.

Nintendo first revealed the game as “Paper Mario 2” at the 2003 Game Developers Conference, commonly referred to as GDC. During the conference the game was confirmed to be a direct sequel to the original Nintendo 64 game and was tentatively referred to as “Mario Story 2” in Japan and “Paper Mario 2” else where.

The game is set in the town of Rogueport, a town that was built on top of an ancient seaside town that was destroyed by a disaster and sunk into the depths of the earth. Legend has it that the fortunes of the lost kingdom are hidden behind the Thousand-Year Door, located in the ruins of the former kingdom. Mario’s involvement begins when he receives a letter from Princess Peach informing him of a treasure map that she had purchased in the town of Rogueport.

The letter asked Mario to assist her in the search for the treasure however upon Mario’s arrival to Rogueport he discovers that the Princess has gone missing. With the help of Goombella and Professor Frankly, Mario learns that the map that Princess Peach included in the letter that was sent to him has the potential to reveal the location of the seven legendary Crystal Stars. These Crystal Stars are required to unlock the Thousand-Year Door which is believed to be where the treasure the Princess is looking for is located. Working off the assumption that the Princess is trying to find the Crystal Stars herself to gain access to the treasure, Mario sets off using the map in an attempt to find the Princess. However, the Princess was actually captured by the Secret Society of X-Nauts, a group of Moon-dwellers led by Sir Grodus who was also in search of the Crystal Stars.

Players take on the role of Mario in search for the Crystal Stars, the Thousand-Years door and ultimately Princess Peach. Along the adventure Mario is accompanied by several characters to form a party to assist in the adventure, following in the tradition of the original “Paper Mario” for the Nintendo 64, Mario can only be accompanied by one additional character at a time. Throughout his journey, Mario is accompanied by a total of seven different party members, a Goomba named Goombella, a Koopa named Koops, Madame Flurrie a wind spirit, a Yoshi, Vivian the Shadow Siren, a Bob-omb named Admiral Bobbery and Ms. Mowz a white mouse.

The game received critical acclaim upon release and is often cited as the best game in the Paper Mario series by fans. Nintendo has continued to expand on the series with the release of Super Paper Mario for the Nintendo Wii, Paper Mario: Sticker Star for the Nintendo 3DS and Paper Mario: Color Splash for the Wii U.