Pokemon Ruby [GBA]

Gameplay

The basic mechanics of Ruby and Sapphire are largely the same as their predecessors'. As with all Pokémon games for hand-held consoles, gameplay is in third-person, overhead perspective and consists of three basic screens: a field map, in which the player navigates the main character; a battle screen; and the menu, in which the player configures his party, items, or gameplay settings. The player begins the game with one Pokémon, and can capture more using Poké Balls. The player can also use his/her Pokémon to battle other Pokémon. When the player encounters a wild Pokémon or is challenged by a trainer to a battle, the screen switches to a turn-based battle screen where the Pokémon fight. During battle, the player may fight, use an item, switch his/her active Pokémon, or flee (the last not an option in battles against trainers). All Pokémon have hit points (HP); when a Pokémon's HP is reduced to zero, it faints and cannot battle until it is revived. If the player's Pokémon defeats the opposing Pokémon (causes it to faint), it receives experience points. After accumulating enough experience points, it may level up; most Pokémon evolve into a new species of Pokémon when they reach a certain level.

--Taken from Wikipedia