It may be an oldie, but it's certainly a goodie as well. Even if 2003's inaugural Call of Duty lacks the sophistication of the later Modern Warfare games, it built the successful foundation which would be expanded and bettered by what would follow. The most revolutionary feature in this ground-breaking FPS is the abandonment of the so-called "lone wolf" gameplay of most other WW2 shooters, in exchange for team-based action which, above all else, just made a lot more sense in the context of a war. This team-based dynamic would ultimately come to define the series (not to mention the war shooter genre), and has made for a successful single-player formula ever since. Even if the campaign is infuriatingly short and the multiplayer mode lacks the depth of the later entries, Call of Duty looked great, sounded great and played great (for the time, anyway), ensuring it scooped up countless Game of the Year awards, an honour it only shares with one other game in the series, Modern Warfare.