Ragnarok Online (Korean: 라그나로크 온라인, alternatively subtitled The Final Destiny of the Gods), often referred to as RO, is a massively multiplayer online role-playing game or MMORPG created by GRAVITY Co., Ltd. based on the manhwa Ragnarok by Lee Myung-jin. It was first released in South Korea on 31 August 2002 for Microsoft Windows and has since been released in many other locales around the world. The game has spawned an animated series, Ragnarok the Animation, and a sequel game, Ragnarok Online 2: Legend of the Second, is in development. Player characters exist in a world with a player environment that gradually changes with the passage of time. Major changes in the features and history of the world take place as episodes in the RO timeline. Player characters interact in a 3D environment but are represented by 2D character sprites for front, back, side and diagonal facings. The major types of server-supported gameplay are Player vs Environment, Guild vs Guild, Player vs Player. Also supported by the game server are Group vs Group, Arena Combat, Player vs Monster, Player vs All, and various other specific scenarios at designated instance locations in the game world. NPC-run challenges and contests are also available with prizes, awards, and/or listing in a specific hall of fame listing.