Match Cards (Concentration)

Match cards is another simple Mini-game. To play, two players are needed, and one of them needs a Deck of cards. To make a deck, 100 monster cards are needed. Talk to Chico in Ludibrium or Casey in Henesys Game Park to create one. Monster cards are EXTREMELY common in GlobalMS, so many people have decks of cards. Once a deck has been acquired, the game is played in a window resembling Omok's. At the beginning, after choosing a hard/medium/easy difficulty, the cards are revealed and flipped over one by one to be face down. Matches must be made by remembering where cards are. Every time a correct match is made, that player gets to try again until failure. In easy games, this can result in the player who gets the first turn winning before the second player even gets a chance to go. If a new player enters the room, the host will go first. Otherwise the loser of the previous game goes first. Since the owner of the game can kick people out, this method is sometimes abused to get a very high win/loss record. Games of Match Cards can also result in a tie, since points are attributed for each match made. Occasionally, guilds or other organizations will hold tournaments.

Match Cards is available in every version except EuropeMS
http://strategywiki.org/wiki/MapleStory/Quests/Mini-Games