According to Modern Warfare gameplay director Jacob Minkoff, characters in Modern Warfare's singleplayer campaign will react to your actions in missions. They will call you out if you do something immoral and comment on those actions.
Earlier this year, before Infinity Ward and Activision even officially revealed their new Call of Duty game, leaks and rumours suggested that Modern Warfare reboot will be inspired by the controversial missions from Modern Warfare 2 - No Russian.
Shortly after the announcement, we got reports that claimed how Infinity Ward is making Call of Duty Modern Warfare the most violent game in the series with graphic missions that show dead children and worse.
The developers already confirmed that players will have many choices throughout the singleplayer campaign that will question their morality and change the story in some ways.
Today, Call of Duty Modern Warfare gameplay director Jacob Minkoff talked about these choices and actions in an interview with Kotaku. According to Minkoff, your decisions or actions will be reflected in game, with different dialogue and actions from characters that follow you in the story.
"The story itself is linear but in the context of the mission, if you go up to the line but you don’t cross it, what you will end up with is characters saying things like 'Dude, what did you just do? God damn it. I hope nobody hears about this,'" Minkoff explained.
Based on your actions, which may or may not be understandable, your dialogue with Modern Warfare characters will branch and in some extreme cases, their performances will also branch - they will call you out on it and there will be other animated performances.
While this is far from a story that will develop based on your choices, it is the first time that Call of Duty is trying to do something different with its campaign. Hopefully, they pull it off, just like they did with the original game, which still has one of the best singleplayer campaigns in the whole franchise.