It should be pointed out that the original article is a bit off - Both Nexuiz and Alien Arena have had steady, if not increasing playerbases over the last couple of years.
That said, a new version of Alien Arena is being released this week. This game has made major improvements in gameplay, content, and engine in the lastest releases, and it continues again in version 7.21
Alien Arena is a game that was built from the Quake2 and Quake3 sources, but bears very little resemblance to either of these games by now. This game looks, feels, and plays much more like Unreal Tournament 2004 that the Quake series. The game still incorporates much of the Quake physics, while adding UT style dodging, alternate firing modes, and a weapon set that has been tweaked and balanced to perfection. Alien Arena also has a wide variety of game modes, such as Cattle Prod, CTF, All Out Assault, Team Core Assault, Duel, and Deathball, as well as incorporating a load of built in mutators to alter the game mode such as instagib, class based, rocket arena, etc.
The engine has received a great deal of attention since June, and has been extensively rewritten making use of GLSL shaders to achieve effects like parallax/specular/bump mapping, as well as realistic water shaders. There has also been much optimization of the code and improvement of basic particle effects. It has been made into a lean, clean, deathmatch machine that plays very well online, with clean, solid, and proven netcode. Antilag options have also been added for those who prefer that sort of thing.
A number of new maps have been added, as well as some of the old standbys being reconstructed to meet the new standards this game has set for itself. The level of detail and polish is something that IMO stands out in a big way. You won't find boxy levels with misaligned textures or boring walls in Alien Arena.
Best of all, despite all of the enhancements, the game is still very scaleable, and can be made to play on very modest systems. Even with the additional detail, the performance far exceeds that of last year's versions.
Alien Arena has a solid, very dedicated player base that is friendly and always eager to help out new players.
Get the game at http://red.planetarena.org/
I've looked at the listing, and it's right! -- Joel Halpern