The Pokémon series of role-playing vieo games features many different concepts, items, and a variety of creatures to tame. Each generation of games has introduced more of these, attracting new gamers and keeping veterans entertained. Some of the general concepts were introduced elsewhere before being introduced in the games: double battles appeared in the anime long before appearing in the games, and Pokémon abilities are similar to the Pokémon Powers introduced in the Pokémon Trading Card Game.