One Piece for the Game Boy Advance is a portable game made exclusively for the handheld system for the American market. It was developed by Dimps corporation, published by Bandai and released in the U.S. in 2005. As the game was made around the time 4Kids held the series license, much of their naming conventions were used in the game.
Players control Luffy through the entirety of the game as they make their way through the stages, fighting generic pirates, marines and henchmen. Luffy starts out with a few moves at his disposal, but as the game goes on, he gains more and more in his arsenal to help him defeat his enemies. Other members of his crew like Zoro, Usopp, Nami and Sanji are also playable in the form of brief summons, to either help clear out enemies or support Luffy in some other way (For example, Sanji can cook Luffy a meal that will restore him to full health). True to form within the series, the bosses get tougher as the player progress each with their own innovation in their boss battles which the player must overcome to defeat them.
Much of the game's content is reused from the prior Grand Battle! Swan Colosseum (also developed by Dimps); the music is remixed straight from said game, and many of the characters sprites and animations are reused from there as well.
Also tying into Dimps, the gameplay of the game follows a very similar formula to the other Shonen Jump game Dragon Ball: Advanced Adventure (also for the GBA).