One Piece for the Game Boy Advance is an action game released exclusively for the American handheld market. It loosely adapts the entire East Blue Saga, chronicling the adventures of the first five Straw Hat Pirates and their ultimate voyage for the Grand Line. It was developed by Dimps Corporation, published by Bandai, and released in the United States in September 2005.
As it was made in tandem with the 4Kids anime, the game uses many of the same naming conventions.
The game is a standard side-scrolling beat-'em-up, featuring Luffy as the sole playable character against a variety of enemies. Luffy begins with several of his trademark techniques, both short- and long-range; as the game progresses, several more can be unlocked to supplement both combat and exploration.
In addition to a standard life bar, Luffy carries a multi-tier "power" bar to fuel his stronger attacks with. This bar is recharged whenever he successfully hits an enemy; different attacks supply different amounts of charge.
Luffy may encounter a variety of helpful items throughout the game. These include:
- Apple: Restores a small amount of life.
- Rice Ball: Restores a large amount of life.
- Drumstick: Restores full life.
- Jolly Roger: Grants one tier of power.
- Luffy Head: Grants one extra life.
- Fist: Grants fifteen seconds of invincibility.
- Bomb: Can be thrown to damage enemies, or break otherwise-unbreakable barriers.
Items may be found out in the open, or in easily-broken crates.
Stories mode, featuring two difficulty settings, adapts the East Blue Saga into six levels.
- Navy Base (comprising Alvida's ship as well as the Shells Town base)
- Port Town
- Syrup Village
- Arlong Park
- Rogue Town
Each level consists of three stages - two focused on platforming and exploration (though usually featuring one or more mini-bosses) and the third centered on a boss battle. Once a stage is cleared, the player's score (measured in Belly to represent Luffy's growing bounty) is tallied, based on the number and prominence of enemies defeated. The stage may then be re-played indefinitely.
As per canon, each level - except the last - ends with a new Straw Hat Pirate joining Luffy. These crewmates serve as a non-player support party in following levels, each holding two techniques which Luffy may substitute for his own.
- Zolo: Charges enemies in a straight line or strikes them with a tornado.
- Nami: Steals one item from an enemy or strikes all visible enemies with lightning.
- Usopp: Stuns enemies with rotten eggs or strikes them with explosives.
- Sanji: Delivers a series of kicks or delivers a drumstick that restores full health.
At the start of every platforming stage, Luffy's available crewmates will wander off ahead; in order to use them, Luffy must find and add them to the party. In contrast, boss stages always begin with a full party.
Levels are bridged by the Ship Battle Royale mini-game, which tasks Luffy with defeating a swarm of enemies aboard the Merry within 60 seconds. If successful, Luffy will earn a number of extra lives based on how quickly he finished.
Mini-Games mode is unlocked after all six levels of Stories mode have been cleared (on either difficulty).
- Ship Battle Royale: A modification of the Stories mode mini-game, featuring no time limit and infinite enemies.
- Boss Rush: A "bonus" mini-game unlocked by gathering the fifty coins hidden throughout Stories mode, stringing all of Stories mode's boss battles into a single challenge.
Fifty collectibles, referencing various items and oddities from the series, can be found throughout Stories mode. Some are automatically awarded for defeating particular bosses; others must be found by interacting with various non-player characters, or achieving a specific score.
Collectibles generally have no effect on gameplay; a notable exception is the Treasure Key, which allows the many treasure chests scattered throughout Stories mode (a common source of coins) to be opened.
Each level also contains one miniature treasure chest; these cannot be opened, but become collectible once the Gaimon NPC (located in the second Syrup Village stage) has been found. Bringing all six chests to Gaimon will unlock the Sound Test, making the game's soundtrack available at leisure.
- The game's box art is modified from that of One Piece: Grand Battle (the English localization of One Piece: Grand Battle! Rush!).
- Most of the game's sprites and animations are recycled from Dimps' previous One Piece game Grand Battle! Swan Colosseum. The music is largely remixed from that of Swan Colosseum as well.
- The gameplay is also very similar to that of Dragon Ball: Advanced Adventure, another Shonen Jump-licensed game developed by Dimps.
- This is the only English-language One Piece game to go further in censoring Sanji's cigarette than simply removing it, recoloring it to look like a drinking straw in all of Sanji's sprites.
- In addition, the Baratie level features the infamous lollipop as a collectible.