One Piece: Treasure Battle! (トレジャーバトル!, Torejā Batoru!) is a party game for the Nintendo Gamecube, published by Bandai and released in November 2002. It was the first One Piece game designed for a sixth-generation console, as well as the first to feature fully three-dimensional gameplay.

Story 
There is a special competition called the "Treasure Battle" clash which is being hosted in the Grand Line on a special series of islands. The Blueberry Times newspaper is covering the events via journalist Rocky Hattari. The Straw Hats, along with Vivi and Ace, should trust each other and work together in a group made of two members and battle through various events to get Treasure Cards. The Treasure Cards are said to give the possessor happiness and can make wishes and dreams come true. The Straw Hats, Vivi, and Ace decided to compete. Luffy and Vivi pair up together. Zoro and Ace, who were not interested in the treasure but their competitive sides are rubbed, so they join "just to win". Sanji followed Nami, who is joining for the treasure. Chopper was amazed hearing that Usopp had a plan. Thus, the teams were decided.

Playable characters 
 Ace
 Alvida
 Arlong
 Mr. 2
 Buggy
 Crocodile
 Don Krieg
 Luffy
 Mihawk
 Nami
 Miss All-Sunday
 Chopper
 Rocky Hattari
 Shanks
 Smoker
 Sanji
 Tashigi
 Chopper
 Vivi
 Zoro

Gameplay

Scenario 
Story mode. There are 4 stories to choose from:
 Luffy and Vivi - 'Easy mode'.
 Zoro and Ace - 'Normal mode'.
 Sanji and Nami - 'Hard mode'.
 Usopp and Chopper - 'Very Hard mode'.

The player will fight 3 Treasure Battles in a row, then have a special mini game for the 4th, and then a best-of-3 round Treasure Battle for the conclusion.

A Treasure Battle is a fight between two teams. The team that can successfully carry a treasure to a goal, preventing the other team from taking it until time up, wins. After winning a Treasure Battle in the story mode; players get a Treasure Card.

Match-up 
The player chooses the stages and characters.

Game modes

Treasure Battle 
"Treasure Battle" is a (two-player-in-each) team game, and has players grabbing a treasure chest and putting it into a boxing ring at the end of each island level, then literally waiting for their ship to come in. Once their pirate ship arrives, that team wins. A team can throw the chest to each other over a limited distance, lob it in the direction they are facing over a greater distance, or even use it to attack the members of the opposite team who are doing their best to grab the treasure chest and take it back to their own boxing ring, and their awaiting pirate vessel.

The screen is split in the "Treasure Battle" according to how many human players are involved. In one-player mode, the full screen allows a decent view of the action, but the 2- and 4-player splits reduce the action to an extremely small view that can make it very hard to determine what is really happening.

Battle Royal 
"Battle Royal" is a similar game to "Treasure Battle", except there is no chest and the arena is more confined. Each team just bashes the opposition about, as much as possible, for just under 3 minutes. All players are displayed on the full screen, which will zoom in and out depending on the spread of the action.

Kung Fu Survival 
"Kung Fu Survival" both teams are placed on to a very small island inhabited by large numbers of Kung-Fu Dugongs. Whichever team beats up the most dugongs within the time limit wins. The player can walk right up to a dugong and attack it in the face, or if they choose Zoro they can have him attack with a kendo. The dugongs are basically defenseless, but if a player is standing motionless, may wander over and attack with a headbutt or flipper strike.

Team Work Rally 
"Teamwork Rally" has each team passing the chest to each other across gaps that can't be jumped over whilst carrying the chest. The race to the finish is a careful balance between taking risks to get the edge over the opposition and being careful at other points to avert disaster.

Cross Country 
"Cross Country" is an individual race to the end of each stage of a longer race. Each player gets a score based on their position at each intermediate stage and the team scores are totaled at the end of the whole race. The race is conducted along a series of different jumps, ladders, islands and narrow passageways.

Pirate Soccer 
"Pirate Soccer" is pirates playing soccer. Except the ball is enormous and can crush the players if they fall under it. They have to use their attack moves to push the ball through goals at each end. Each half is 90 seconds.

Treasure Hunt 
"Treasure Hunt" has players wondering around randomly until an arrow appears, directing them to hidden treasure.

Trivia 

 The game presents Rocky Heart, a non-canon character present only in the game. Rocky talks a lot in English and plays guitar.

Other websites 
 Official website 
 Nintendo mini-site 

2002 video games
Party video games
Fighting games
Video games based on television shows
Japan exclusive video games
Anime
Nintendo GameCube-only games
Nintendo GameCube games