This torrent is filed under Windows Games but it is in fact cross-platform, fully working on Linux, Mac and Windows.
From the readme:
Upload made by Spanky (natenkiki2004)
The mAAp Pack Project Server Version + 2.5 Assist
The mAAp Pack Project is a collection of custom maps for America's Army 2.5. In this release (5.0), there's about 28 custom maps that fully work online, a custom GUI, added graphics and more. The most promising map is our new Pipeline:
This version of the mAAp Pack is for remote servers. This is not for client use. To play the mAAp Pack please use one of the 2.5 Assist programs in this torrent.
2.5 Assist is a Installation Utility for America’s Army, It is deigned to make the process of Installing and getting up and running with AA as easy as possible.
If you are new to the game this little Application will fully automate the download and installation of the game from it’s own repository server and handle all the needed updates and checks. It will then guide you through the process of creating an account and then load your account details automatically when you first play.
Getting up and running with this free game is now as easy as a few clicks of the mouse.