Japanese mobile social giant GREE suffered a 6.15% drop in its stock price today after reports of users exploiting a bug in their top game hit the media. The game, Tanken Doliland, is a social card game battle with RPG elements. A bug in the game makes it possible to copy and distribute any virtual card. Some of the cards in the game are very rare and almost impossible to get, until users started auctioning them off on Yahoo Japan's web site, some for over $300.
Tanken Doliland is Gree's number one game, raking in $26 million per month in virtual item sales, and it has been the top-grossing app in the Japanese App Store (it's at #5 now). When queried by business daily The Nikkei, GREE today admitted the existence of the problem and says it's working on fixing the bug. Investors do not seem reassured that the game will continue to do well.
The bug apparently involves using two accounts on two cell phones. A player sends the original card to the second phone, and then the same user on both cell phones receives the sent card by pushing buttons on the two phones simultaneously. One seller sold 7 copies of the same rare card for ¥30,000 (about $377 US) within 3 hours around the time when the story of the bug first appeared. Apparently the game is not adequately identifying individual phones and users, or locking out simultaneous access to an account.
