Marathon, Marathon 2 and Marathon Infinity are single and online multiplayer old school 1st person shooter games.
Aleph One is the open source continuation of Bungie™’s Marathon® 2 game engine and played these games.
Many third party scenarios and net maps are also available. Available for Mac OS X, Windows, and Linux.
This package includes the Marathon trilogy.

To run:
  Menu -> Games -> Marathon, Marathon 2, or Marathon Infinity

To run in a terminal: 
  /usr/local/bin/alephone ~/AlephOneData/Marathon/
  /usr/local/bin/alephone ~/AlephOneData/Marathon_2/
  /usr/local/bin/alephone ~/AlephOneData/Marathon_Infinity/