Nintendo's monster-battling franchise makes its Game Boy Advance debut with the simultaneous release of Pokémon: Ruby Version and Pokémon: Sapphire Version, which differ in the frequency of certain monster types. While gameplay closely follows the framework established in earlier titles in the series, a number of enhancements have been incorporated. The world in which players explore is entirely different, as are the strategies associated with the turn-based battles. Certain matches have players selecting two different Pokémon to fight their rival's two creatures, allowing for more choices in combat. The setting for both versions is the region of Hoenn, a chain of islands featuring a variety of climates and terrain, including mountain areas, arid deserts, murky swamps, and more. A total of 15 cities are available to explore, each filled with local residents and fellow trainers who will challenge players to hone their battle skills. Players will be able to carry a party of six Pokémon at once, after first catching them in the wild, with others stored in boxes accessible from each city's personal computer network. Tools or machines can also be acquired to perform tasks such as chopping down trees, fishing, surfing, planting berries, smashing rocks, and even flying. One hundred new monsters have been added into the mix, upping the total of catchable creatures to 200. Ensnared Pokémon are automatically catalogued within an upgraded Pokédex, whether it's the shark-like Sameheader or the pelican-inspired Pelipper, requiring players to learn their special abilities as they evolve into more powerful types. Backgrounds in the fight scenes are now depicted in different shades of color, and the backpack introduced in Pokémon: Gold and Silver has been replaced with a roomier utility belt to carry items found along the journey. Unlike previous games in the popular series, players are unable to transfer existing Pokémon from earlier titles on the Game Boy and Game Boy Color.