Ragnarok Online - European Version had Steam trading card support added on December 3, 2013. There are 8 cards in the series. Because its a Free to Play game, cards are earned by spending money in the in-game store.
This version of Ragnarok Online is only playable in Europe. The American version of the game, Ragnarok Online, has a different set of Steam trading cards. Though Americans cannot play the European version of the game, they can collect the cards (via marketplace or trading) and craft the badges.