The original Modern Warfare became our official Game Of The Generation, appearing on all of our blind tallies. As the shock wore off, we gradually realised that democracy hadn't failed us as badly as we thought. Modern Warfare was utterly superb, both in terms of its grounded singleplayer campaign, seminal set pieces and multiplayer that set the trend for years to come. It's a ruddy masterpiece, and you can grab a copy (for 'All Ghillied Up,' basically) for £3.49 on GetGames. It's SteamPlay, so will work on both Mac or PC.
Thanks to jaystan @ HUKD!