First launched in South Korea in 2003, MapleStory has grown to become one of the biggest online games in the world, with over 92 million registered accounts.
MapleStory Europe, which has 1.2m registered players, will get an extensive patch on October 22.
The update will introduce a new map around the medieval town of Magatia, which is the residence of two warring alchemist groups called the Alcadno and Zenumist.
Players taking part in the quest will have to solve various challenges to settle down the conflict between the two parties and restore harmony to the town.
"We just had the Ariant map added to MapleStory Europe in September, and bringing another new map just after one month may be a challenging task" said Nexon Europe director Sung Jin Kim.
"But the loyalty and enthusiasm of our players is huge and we really feel the need to keep up with their stunning digestive power for game content."
The Halloween season will also be celebrated in the update with the story of Prendergast, a toymaker who used to be a happy until something terrible happened to him.