Modus - Engine
Project created by Jay Manley (Xtreme)
Created in 2008. This source was basically a customized version of Nevaria with a few tweaks. The source was eventually leaked and obtained by 3rd parties which lead to other servers being created with this source.
This engine is now open source! You can get a copy of the source (and a binary compiled for local testing) in the downloads section.
How To Play
Download the source code for this engine in the download section