MegaGlest, being open source, is available for many Operating Systems, and since no one operating system works the same, it's necessary to use different methods to get Glest for your operating system.
Windows and Mac OS X
The easiest way is to download the installer from MegaGlest Downloads.
There is a patch to port Glest V2.0.0 to FreeBSD on the FreeBSD webpage
Also see Compiling Megaglest for FreeBSD
This is the easiest way to install MegaGlest. Open the package manager of your distribution (f.e. synaptic package manager, Kpackage manager, yast, ...), search for MegaGlest, and install it.
Or on ubuntu or debian: open a terminal and type: "sudo apt-get install megaglest" enter your sudo password, and after downloading, MegaGlest will be installed.
Pbone.net has RPMs for Suse, Mandrake, Mandriva, PCLinuxOS, and FedoraCore.