I ran across this thread on a deals forum today that explains how to download the re-released version of Mechwarrior 4 Mercenaries for Free. http://slickdeals.net/forums/showthread.php?sduid=158165&t=2004520 the re-released version includes additional content that the original did not and its free.
I used to love playing the MechWarrior games. They have a open source version if you have the Crysis Engine. www.mechlivinglegends.net
there are a couple of alternate download links such as : http://www.fileplanet.com/211699/210000/fileinfo/MechWarrior-4:-Mercenaries-(Free-Game) http://www.megaupload.com/?d=AL579RW9 http://www.megaupload.com/?d=LUGVQO17 the main site seems to be getting slammed atm