QuakeWorld

QuakeWorld (abbreviated QW) is an update to id Software's seminal multiplayer deathmatch game, "Quake", that enhances the game's multiplayer features (namely UDP support) to allow people with dial-up modems to achieve greatly improved responsiveness when playing on Internet game servers. Modern broadband connections such as cable and DSL can use the QW network handling and game physics as well. Official id Software development stopped with the test release of QuakeWorld 2.33 on December 21, 1998. The last official stable release was 2.30. QuakeWorld has been described by IGN as the first popular online first-person shooter.
Gameplay.
Other than the networking improvements, QuakeWorld's gameplay is identical to Quake's multiplayer mode.
Development.
"Quake" network code, the part of the software that handles multiplayer gaming over a network, was designed for low-latency play over a local area network (LAN). The original "Quake" did not address the fact that Internet connections have generally much higher latency and packet loss compared to a LAN connection, and over some connections, performance of this model did not provide an optimal experience. Therefore, QuakeWorld introduced "client-side prediction" (CSP).
After months of private beta testing, QuakeWorld, written by John Carmack with help from John Cash and Christian Antkow, was released on December 13, 1996. Further development was later taken over by David Kirsch and Jack Mathews. It included a useful program called QuakeSpy, written by Mathews, which later evolved into GameSpy.
Legacy.
After the GameSpy shutdown, the QuakeWorld community host up a server and a website under the URL quakeworld.nu