Pokémon Emerald (ポケットモンスター エメラルド Poketto Monsutā Emerarudo, lit "Pocket Monsters: Emerald"), featuring Rayquaza on the box art, is the twelfth game in the Pokémon video game series in Japan, and the eleventh in North America and Europe. The game, an updated version of Ruby and Sapphire, was released in Japan on September 16, 2004; it was released in North America on May 1, 2005; Australia on June 9, 2005; and Europe on October 21, 2005.
Although the gameplay is as that of Ruby and Sapphire, Emerald introduces new features. The plot is modified; both Team Magma and Aqua are villains who are locked in a constant gang war and awaken Groudon and Kyogre, respectively. When the two legendary Pokémon begin to battle each other, the protagonist must unleash the legendary Pokémon Rayquaza (pictured on the box cover) to calm them. Some of the game mechanics are changed as well. Though double battles were clearly marked in Ruby and Sapphire, in Emerald, two separate trainers might unite to battle as a pair. After the Elite Four is defeated, the player may re-battle Gym Leaders in a double battle if they are called on their PokéNav. Also, Pokémon sprites are animated in battle like they were in Pokémon Crystal. Probably the most significant addition is the Battle Frontier, an expanded version of the Battle Tower in Ruby and Sapphire.