I take it this is an online only game like AH?
MW4 is an awesome MechWarriors game released by Microsoft several years ago. It has both single player missions and multi-player online capabilities. Basically it was cutting-edge for its day both in graphics and interface... but now it's for the most part, obsolete.
Another company has recently gotten permission from Microsoft to release this game for free. Basically they went in and changed it just a bit to make it more compatible and added a few minor things and now allow you to download and play it for free using their software. (I was also able to download Battletech: Assault Tech 1.. an even OLDER version of MW from their software). I actually have the disks from the MW4 game I played years ago, but last time I installed it, I could not get it to work properly with my X52. This version works great though!
The rumor is that Microsoft is getting ready to release a new MW game in the near future, so they are trying to get a whole new generation hooked on the crack before it happens...