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 conventional 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 (tied to a finite number of lives), Luffy carries a multi-tier "power" bar to fuel his stronger attacks with. This bar is recharged whenever Luffy 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 to the technique bar.
- 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.
While the other Straw Hat Pirates are not playable, they can - under proper conditions - be accessed as support characters for Luffy. Each can be summoned to perform one of two special techniques.
- 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 roast that restores full health.
Summoning crewmates will deplete the power bar, in effect substituting their special techniques for Luffy's own.
Stories mode, featuring two difficulty settings, adapts the East Blue Saga into six levels. Each level consists of three stages:
- A "platform" stage, focused on exploration, where Luffy must navigate numerous paths (and enemies) to reach a Jolly Roger checkpoint.
- A "hybrid" stage, where Luffy must navigate numerous paths (and enemies) to reach and defeat a boss character.
- A "versus" stage, free of exploration, where Luffy must defeat the level's main boss.
In addition to ordinary enemies and bosses, levels may contain one or more "mini-boss" enemies that typically retreat when struck; these have no bearing on game progress, but often provide unique bonuses if defeated. Each level also contains several stationary characters that produce dialogue when approached; these may also enable various bonuses.
Once a stage is cleared, the overall 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 any number of times.
As per canon, each level - except the last - ends with a new Straw Hat Pirate joining Luffy, building a party to be used in following levels.
- Non-versus stages will begin with Luffy's available crewmates wandering off ahead; to use them, Luffy must find them one-by-one and restore them to the party.
- Versus stages will begin with all crewmates gathered in the last-completed stage.
Levels are bridged by the Ship Battle Royale mini-game, which tasks Luffy with defeating a set number of enemies aboard the Merry within 60 seconds. If successful, Luffy will earn a number of extra lives based on how quickly he finished.
Clearing all six levels of Stories mode (on either difficulty) will unlock Mini-Games mode, featuring a high-scoring version of Ship Battle Royale. In this mode, the game has no time limit and infinite enemies; the only objective is to defeat as many as possible.
Three difficulty settings are available:
- Easy, with ordinary pirates as enemies
- Normal, with Navy recruits as enemies
- Hard, with Fish-Men as enemies
Finding all fifty of the coins hidden throughout Stories mode will unlock the Boss Battle, where Luffy must fight all twelve (mandatory) bosses back-to-back. No continue option is provided; losing on any stage will immediately end the challenge.
Three difficulty settings are available:
- Easy, with a full crew at hand, enemies at minimal power, and full health restored between battles
- Normal, with a full crew at hand, enemies at standard power, and 90% health restored between battles
- Hard, with no crew at hand, enemies at maximum power, and 80% health restored between battles
Fifty collectibles, referencing various items and oddities from the series, can be found throughout Stories mode. Some are automatically awarded for clearing a level; others can only be obtained by interacting with specific characters, or reaching a specific score.
Most collectibles have no effect on gameplay. A notable exception is the Treasure Key, which allows Luffy to open the many treasure chests (a common source of coins) scattered throughout Stories mode.
Each level also contains one miniature treasure chest; these cannot be opened, but become collectible once Gaimon (hidden in the Syrup Village level) has been spoken to. Bringing all six chests to Gaimon will unlock the Sound Test, which contains the game's entire soundtrack.
- 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 American-released 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.
- All three will attack at various points throughout the first two stages. Unlike mini-bosses, however, they cannot be defeated until they are confronted at the end of the second stage.
- Re-playing a stage after the level's boss has been defeated is often mandatory for completing certain side-quests.
- Rogue Town's hybrid stage breaks from this pattern; it contains no crewmates and must be cleared by Luffy alone.