It’s a much more advanced system, changing the world as you will travel through it.
One of the features behind the success of Shadow of Mordor was the Nemesis system. If you are new to the IP, it’s a unique solution that creates randomized enemies with their own backgrounds. Your actions in the world change the hierarchy of Sauron’s army and even influence how you are treated by each boss.
In Middle-earth: Shadow of War the Nemesis system will be much more expanded thanks to armies and forts. Not only will you gather your orcish followers, but also promote them and decide which of them will lead various fortresses and camps. The surroundings of each fort will transform according to their origin, as well.
IGN First has another gameplay video narrated to give you a better understanding about the new features: