Gamers are just a month away from experiencing the latest chapter in the immensely successful Call of Duty franchise, Advanced Warfare, which from what's been shown off so far suggests one of the series' most original entries in quite some time, boasting truly next-gen visuals and, well, Kevin Spacey. To commemorate that release, let's look back at the 10 main entries into the franchise to date, going all the way back to 2003's original Call of Duty, observing how it's shifted over the years, and deciding which games are the best, and which just don't quite stand the test of time. Though the franchise has earned significant (and fair) criticism over the years for failing to innovate, each subsequent entry (especially from Modern Warfare onwards) has sold by the truckload, so Activision are clearly doing something right, even if pre-order projections for Advanced Warfare suggest that the CoD bubble is slowly deflating (though it's likely always going to be a good seller). As Advanced Warfare's release nears, let's examine the highs and lows of the most popular FPS franchise in existence, from its more noble origins, to the bombastic status it holds today. Here are the 10 core Call of Duty games ranked from worst to best.