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Yu-Gi-Oh! Official Card Game is the version of the Yu-Gi-Oh!
card game manufactured by Konami. It is played mainly in Japan and parts
of Asia. The OCG is printed in Japanese and Korean. It has previously
been printed in English (refered to as Asian-English) and has also had 3
different Chinese prints of cards, including two "Blue-Eyes White Dragons" and a "Dark Magician".
Generally, the legal status of a card is the same in the Japanese version of the game as it is in the Advanced Format, since the Advanced Format is designed for international tournaments. However, there will occasionally be a card Forbidden in the Japanese cardlist, and be outright Illegal in the TCG.
With the exception of TCG only cards, TCG
cards are legal in OCG tournaments. Due to the cards having different
backings, if a player chooses to use a mixture of OCG and TCG cards,
they must use protective sleeves that cover the back of the cards.
However in some parts of Asia, local sanctioned tournaments have
restricted the use of TCG cards.
OCG tournaments are divided into three classes: Expert, which has
no age restriction, Regular: for secondary school students and
Challenge, for primary school students."