Latest stable version
After downloading the game from the official website, run the installer. When it is finished installing, run the Alien Arena program to launch the IRC client/server browser, or the Alien Arena Quickplay to launch the game directly.
Download the linux zip archive and extract it to your location of choice. To launch the game, run crx.sdl (there is also crx, but this has broken sound, use crx.sdl instead).
Or Please try "sudo apt-get install alien-arena"
should auto install also "alien-arena-data " and "ttf-aenigma" (509mb total)
Run with command line "alien-arena"