This is the first preview build of the open-source Xonotic game and it comes with a smaller set of maps and content than what will be available when the game reaches a 1.0 stable milestone, but it already is 1.3GB in size.
From the release announcement:
The last release of Nexuiz (2.5.2) was on the first of October 2009, and when we decided to fork early March 2010 we continued where we had left off with Nexuiz. Large parts of the code, graphics and music have been redone and have improved immensely. In over a year we have managed to make huge progress on pretty much every part of the game. However this release is still a preview, which means that bugs are likely to exist and that some of our decisions turn out to have unwanted side effects. This first preview also still has a limited number of maps, but we do have many maps being worked on for future releases! In the next sections we will explain what new features are available and the main things that have changed from Nexuiz.
While there are a lot of improvements to the Xonotic visuals over Nexuiz, the developers have shared in the announcement that the game is running well on most hardware out there. They also ended up merging Direct3D support into the DarkPlaces engine, which will benefit those users of Windows or potentially Linux users with the Direct3D 10/11 state tracker. The developers though recommend you have at least 2GB of RAM available for playing this game.
Xonotic also features a new HUD (Heads Up Display), game menu system, major changes to the game's physics and balance support, new player models and animations, new maps, and much more.
This may be the first preview release of Xonotic, but from going over the release announcement and the included screenshots, its looking rather great! Nexuiz 2.5 was already great in terms of its visuals and game-play, but now these former Nexuiz developers have kicked it up by a notch or two.