Ingame Base building:

While playing the campaign you can gain objects in story-/sidemissions and other events. With that objects you can improve bases or even make your own ones.

Reinforcement System:

During campaign you can help and save soldiers or civillians who will be available as reinforcements after completion of your actual mission or after some Time when no mission is active. Also you can capture or find vehicles that you can use as reinforcement if you got enough crewmen.

Story:

Comming after some Time

Dynamic and Interactive Campaign:

During Campaign you can make Descisions for exsample: Your Mission is to attack a camp hold by AAF, how will you engage? The Stealthy way or the Loud one? Will you go in close Combat or will you eliminate your from distance?

Besides that you will be able to decide if you just scavange a taken in Base or if you rebuild it, reinforce it and use it for you own.

Enemys may react to your actions. For example: You decided to ambush a supply convoi. Will the enemy call reinforcements? Will they strike back later? Or will they just leave it that way?

Maybe there will be Story Decisions, depends on the story i'll make.