Like most Pokémon games, in Pokémon Shuffle you play as a new Pokémon trainer, setting out to defeat, catch, and collect Pokémon. Pokémon are cute animals which can be trained to fight with other Pokémon. Despite this basic similarity with animal fighting, the Pokémon games are traditionally great at teaching kids useful skills like strategy, compassion, and even math.
Unlike other Pokémon games, however, Pokémon Shuffle is not an open-world RPG. The player progresses along a linear path of Pokémon, and fights them by matching up images of the Pokémon that they have already caught. There is more strategy to it than that—there are many types Pokémon (fire, dark, electric, etc.) and each type is strong against certain other types and weak against certain others. It's kind of like a big complicated game of rock-paper-scissors. If you're fighting a fire Pokémon, make sure to match up lots of water Pokémon, because the damage dealt will be doubled. The fewer turns it takes you to win the fight, the higher your chances of catching that Pokémon at the end of your fight and adding it to your arsenal.
Pokémon Shuffle is free to download, but like many popular mobile games, you're only given a limited number of turns. If you want to keep playing without waiting around, you'll have to spend in-app treasures or real-world money.