Trepidation is an open source first person shooter based on the IOQuake3 engine. It was originally conceived on April 9, 2006 with the intent to build a free first person shooter with a sci-fi theme. The idea was initially developed by members of the Star Trek Elite Force gaming community.Yesterday, the first development release since 2007 was released. It's mostly fixes but gameplay is affected. For example the sniper scope is more reactive and missing sounds are now in place.
There are 141 MB downloads for 32bit Linux and Windows. For 64bit Linux and other systems there's svn:
svn co https://trepidation.svn.sourceforge.net/svnroot/trepidation trepidation
I haven't had the time to figure out whether or not I need Quake 3 or OpenArena for Trepidation to work. Besides the project page there is a blog and a forum.