In 2003, "Pokémon Ruby and Sapphire" were released. They were the first "Pokémon" games on the Game Boy Advance, and this upset many players because they could not trade Pokémon with "Red", "Blue", "Yellow", "Gold", "Silver", or "Crystal". However, there were 135 new Pokémon, bringing the total to 386. There were many new features, like a PokéNav (a new item used for many ingame tasks), many more kinds of Poké Balls, a far bigger region (Hoenn) than in previous games (Kanto and Johto), and a Battle Tower different from the one in "Crystal". Players could also create Secret Bases, small hideouts hidden in trees and rock walls.