From the official One Piece website:
One Piece Card Game is a collectible card game themed on the world of One Piece!
Characters from all over the history of One Piece, including the anime, manga, and movies, are featured in the game, and there are even cards inspired by famous scenes from all of them!
One Piece Tournaments are held at RSG every Saturday at 5:00 PM. Official Bandai promos and prize support are available to tournament participants.