McWorld codes or mCodes were printed on the packaging of toys included in Happy Meals, but the McWorld site shut down in February 2014. McWorld was an interactive virtual world for children that McDonald’s launched in 2008 on HappyMeals.com.
Once a child registered for the website and selected an avatar and mPet, they could chat with residents, complete quests, solve puzzles, build treehouses and play games. McWorld also featured a marketplace where members could buy and sell mPet accessories and items to decorate their treehouses. McWorld codes were available on cards and on the packages of toys included in Happy Meals. They allowed members to play games and purchase items in the McWorld marketplace.