Warzone 2100 is a free and open-source 3D real time strategy (RTS) game developed by Pumpkin Studios. It was originally a proprietary game but since late 2004, it was released under the GNU public license. You are in command of a faction called The Project, the world has been devastated by nuclear warfare and its your task to battle to rebuild civilisation.
Mac OS X 10.4 or newer
2 GHz Intel powered Mac or faster
128 MB OpenGL compliant graphics card
256 MB RAM
1.1 GB hard disk space
Free download at wz2100.net