D2X-XL is an enhanced version of D2X, the OpenGL modification of the classic shooter game Descent 2. D2X-XL is available for Mac OS X, Linux, and MS Windows. It is well documented and maintained.
Although D2X-XL contains a lot of enhancements and new features, it is still fully backwards compatible to every other Descent 2 version. As many fixes restore features of the original Descent 2 that were missing in D2X (like availability of all cockpit views, or working mouse steering), it is even closer to them than D2X itself.
If you want to support my efforts (e.g. by funding a Macintosh) computer, you can do so by going to my web site and donating. 
Complete version history available here.
What’s new:
Version 1.13.44:
• Fixed: UPD default port still was wrong
• Fixed: Some wrong arithmetic (multiplication instead of addition) applied to a timeout value lead to severe connection problems
• Improved: Now supporting up to 7 simultaneous join requests
• Fixed: UPD connections didn’t work anymore
• Fixed: Players joining a running multiplayer game could spawn inside other players
• Improved: UPD connection speed now depends on packets/second setting and should therefore usually be faster
• Improved: Added code to prevent connection flooding by the same player
• Fixed: Opening and damaged doors looked transparent when lit by the hardware headlight with per vertex lighting
• Fixed: Turning on the hardware headlight with per vertex lighting temporarily switched to the per pixel lighting render path which could cause rendering flaws and crashes
• Fixed: The transparency renderer could freeze the program with per pixel lighting enabled
• Fixed: Particle light trails were black
• Improved: The gatling tracers look a little better
