Online updates - Guild wars is at its heart an example of a Software-As-A-Service (SAAS) which companies have been touting for a while. Whilst you need to install the initial application, the rest of the game is purely updates. And its not small updates either, as new campaigns, new cut scenes, new enemies are all downloaded on the fly. This said, all it needs to download is graphical presentation and input layers only. The original install is apparently just a 90kb 'thin' client and most of the logic in the game is kept on the server. As it gets to a new area, it compares what it needs with what it has and downloads any additional content. This makes it easy for developers to add more content, fix exploits and respond to customer demands.
Instance Network reconnect - The single worst part of RTS games is typically playing a game for 30mins, and be at the climax of a good battle, and then have either the game crash on you OR you get a network disconnect. In Guild wars, each explorable area is a private instance that is just made for you and your party of friends. So if one of you got disconnected for any reason, it would ruin the game for everyone if it wasn't for Guild War's ability to detect disconnects and allow the user to reconnect straight back to the session, allowing the party to continue adventuring.
A Well-Made UI - A common mistake is to have an amazing back end infrastructure and to spend no money on the user interface technology. Guild wars doesn't fall into this trap by having a user experience that is both gorgeous (even after 5yrs, the architecture and scenery in GW is breath-taking) and completely functional (user widgets are adjustable, contains all the information you need, have appropriate short cuts etc). It helps add to the gaming experience instead of detracting as some gaming UIs tend to. To top it off, much of the UI is customizable. You can in fact skin the client, since it doesn't affect any other player. This includes changing some of the graphics or sounds or whatever. This does have some impact in PvP however since you can mod certain classes to be more visible (everyone loves to kill the healers).
I've heard some friends say there isn't anything technologically innovative about Guild wars and it is true. All the above have been done in games before. Guild wars happens to execute many of these things well and this really helps you appreciate the technology behind this game.
Further Resources about the technology behind Guild Wars:
- http://au.pc.ign.com/articles/534/534454p1.html
- http://www.monashreport.com/2007/06/09/technology-of-guild-wars/
- http://www.dbms2.com/2007/06/09/the-database-technology-of-guild-wars/
- http://www.dbms2.com/2007/06/12/thoughts-on-database-management-in-role-playing-games/