Paper Mario: The Thousand Year Door is one of the greatest games of all time.
The plot of the game is that Peach travels to Rougeport, where she meets a mysterious salesman. The "salesman" says that only a pure heart can open the box and get the treasure inside. Peach does, and she gets a treasure map. Hoping Mario can find the treasure, she sends the map to Mario and a letter telling Mario to go to Rougeport and meet her there. Mario arrives in Rougeport, only to find out the princess isn't there. While searching for Peach, he find two X-nauts and Lord Crump cornering a Goomba named Goombella. Mario is drawn to the situation, and after a short battle with Lord Crump, Mario saves Goombella, who tells him to meet Professer Frankly, and joins Mario in his quest. Mario then sets off to find the Crystal Stars and save Peach.
The graphics are amazing. The game has 2-D graphics but has a 3-D envoirment. I know that's odd, but it does a good job giving the game it's unique feel.
The gameplay is simple, yet deep. The battle system is turn-based. You select a command that tells Mario and his partners what to do. However, there are Action Commands. If you do the command correctly, you can do combos, more damage than usual, and more. This really is the thing that makes this game fun.
The controls are excellent. There is only one thing I can say: it has no flaws.
Overall, the game does a good job keeping it a solid package. Excellent controls, great gameplay, and a deep plot make this game a must-buy.