Development
Guild Wars is the first game created by developer ArenaNet. Senior developers from Blizzard Entertainment, some involved in the early development of World of Warcraft, left to create ArenaNet to develop a game which took risks with game design and business model. Guild Wars development was first announced in April 2003. Guild Wars Prophecies, initially marketed simply as Guild Wars, was released in April 2005. Sorrow's Furnace added further playable content to Prophecies in September 2005. Guild Wars Factions was released exactly a year after Prophecies in April 2006 followed six months later by Guild Wars Nightfall in October 2006. A fourth campaign, Utopia, was in development, but after reviewing feedback from fans and the sort of changes they wanted to make, ArenaNet elected to focus on an expansion pack, Guild Wars: Eye of the North, released in late August 2007, and Guild Wars 2.

Guild Wars was developed in an environment following the release of EverQuest where many MMORPGs were proposed. As a result ArenaNet positioned Guild Wars in a niche in the online RPG genre, offering online gameplay without a subscription fee. ArenaNet believed that players prefer not to pay subscription fees for every game they play and paying a fee causes players to make a "lifestyle commitment" to a particular game, rather than switching between different games which they considered to be more usual gaming behaviour. Jeff Strain, a founder of ArenaNet, states "It is our opinion that the free online gaming model combined with frequent content updates is the optimum online paradigm for interfacing with consumers and creating a significant, enduring gaming franchise."

ArenaNet has used open beta testing throughout the development of the Guild Wars series. For the first public appearance of Guild Wars Prophecies in April 2004, that occurred in conjunction with E3 2004, people were encouraged to download the client and play an online demo of the game to test its networking capabilities. This was followed by a preview event and several beta test weekend events. Both Factions and Nightfall had similar test weekends prior to their release. Nearly 500,000 players spent an average of 8.5 hours playing the Nightfall PvE content during its second beta test weekend. In addition to the public beta events, ArenaNet uses continuously running closed alpha test servers; alpha testers are either ArenaNet employees or have signed a non-disclosure agreement with NCsoft. Aspects of both Factions and Nightfall were influenced by player feedback. Gameplay for Prophecies was altered after release to introduce changes to skill capture and experience acquisition and add faction to PvP parts of the game. No further playable content—such as quests and missions—is expected to be developed for players who only own the Prophecies, Factions and Nightfall campaigns. Modifications to interfaces, such as the changes prior to the introduction of Eye of the North and skill balances are applied to players of all campaigns.

ArenaNet also continues to develop in-game events coinciding with real-world events for players of all campaigns. These events feature minigames, quests, town decorations, masks and collectible gifts. Smaller events also occur which include weekends where the rate at which certain items drop while out questing is increased or the rewards from PvP play are improved.

Game engine
The game engine for Guild Wars was developed by ArenaNet. Engine components developed for Guild Wars are available to be licensed to other NCSoft companies and have been used in other NCSoft games. However, ArenaNet have said they will not license the game engine technology to non-NCSoft companies.

Content delivery and network architecture
To support their fee-free approach to online gaming the server architecture developed for the game was core to minimizing the bandwidth costs associated with maintaining game servers. Infrastructure design was influenced by the developers' experiences with Battle.net development.

The game client is available for download as a very small file. Each time there is an update to the game the existing client automatically downloads a new version of the client which examines a manifest of files to determine which files have been modified and therefore need to be downloaded to the client machine. This manifest is prioritized, the most important files are downloaded prior to the player being able to start the game, the rest are downloaded in the background while the player is playing. ArenaNet uses this rapid update technology to make changes on demand and close exploits in the system.

ArenaNet also utilizes their update technology to preload content from new Guild Wars campaigns onto existing players' accounts prior to the release of that campaign. The content is only activated after the right key is added to the player's account and the game servers allow the campaign changes to go live.

The game is server hosted. Much of the game mechanics are performed or verified by the game servers. The Guild Wars servers are set up in a distributed model. Players are presented with what appears to be a single server but their data is moved to different locations or servers depending on where in the world they are playing and server load at the time.