Modern Warfare's single-player campaign will focus on realism and feature tactically-based moral choices whereupon the player is evaluated and assigned a score at the end of each level; players will have to quickly ascertain whether NPCs are a threat or not, such as a civilian woman who is believed to be reaching for a gun, but then simply grabs her baby from a crib. This collateral damage score, referred to as a threat assessment, is based on how many civilians the player injures or kills and ranges from rank A to F. Rewards are introduced to those who score higher. Character dialogue will differ depending on the choices the player makes in the game. Tactical decisions are also included, such as the player using a sniper rifle in a large environment to approach objectives in a non-linear order, and choosing to shoot out lights in favor of using night-vision goggles during breaching and clearing.

The game's multiplayer has been revised to allow for more tactical gameplay, including a focus on map exploration, door breaching, and a "Realism" mode that removes the HUD. The mini-map has been removed in favor of a compass-style marker, with visual cues to detect friendlies and opponents. Multiplayer also features the return of Killstreaks (rewards based on kills), with more recent Call of Duty titles having used Scorestreaks (rewards based on score) instead. The online modes allow for a larger range of players within a map than previous installments, with a new mode called "Ground War" featuring over 100 players, while conversely another new mode, "Gunfight", tasks two teams of two players against each other in small matches lasting forty seconds per round. The game includes an extensive weapons customization system, presenting most guns with a range of up to 60 attachments to choose from (five of which can be equipped at any one time). The introduction at the start of multiplayer matches has also been revamped; while in previous titles players would remain motionless on the map as a timer would countdown to zero, players will instead be transported into the battle zone as part of various animations.

Modern Warfare will be the first game in the series since 2013's Call of Duty: Ghosts not to feature a Zombies mode, instead featuring the cooperative "Spec Ops" mode previously present in Call of Duty: Modern Warfare 2 and Call of Duty: Modern Warfare 3. The Spec Ops mode shares its narrative with both the campaign and multiplayer. The mode will include survival mode which was present in Modern Warfare 3, but is exclusive to the PlayStation 4 release until October 2020.