The missions as well as EVERYTHING else will be random. You will not be playing the same game twice.
Instead of having the missions randomly switched around, each mission will have its own set of random triggers.
For an example, Mission 1 will have a one of 6 different outcomes. Then mission 2 might have 1 of 6 as well. There will be close to 1 of 20 missions. Everytime you play the game you WILL come acrossed a new mission you never seen before, giving more inspiration to playing the game over again, as well as catching players unexpectedly.
Updated- You will also now be able to interact with none player controled units. Starting conversations, getting them to follow you, or they might even ask things of you. Such as ammo, Medkits, batteries ect.
Updated- The player will now also have a bigger role in the game. You are one of the few remaining humans left on earth and became what is known as the "Remaining Human Alliance Units", brought together and made an outpost with other human remaining forces to make a stand and fight off the alien forces.
None.