Call of Duty is the biggest first-person shooter video game franchise ever. With 19 titles released since 2003, on a yearly basis apart from a gap in 2004, Call of Duty has been relentless in its presence throughout the industry. To avoid becoming stale, Call of Duty varies the time and settings of its games, but most notably produced two main sub-series through the '00s and 2010s, Black Ops and Modern Warfare.
Source：https://www.cbr.com/every-cod-modern-warfare-game/
