I'm surprised this hasn't been posted yet... Sierra has released the multiplayer aspect of F.E.A.R. for free. You can download it from here. Should that download be too slow for you, you can find a list of mirrors here. If you already own the full version of F.E.A.R. all you need to do is download the 1.07 update to make your installation compatible with F.E.A.R. Combat. Enjoy.