It s nemesis system,find infinite amount of orc with thousand personalities which change depending on things you do, you can also train your orcs - try to make perfect warrior(just started doing it hassle but I like it), do online sieges and once in while you can get extremely rare Uruks from people who were lucky to get them in their world. You can die to a a normal warrior or a slave and create a legend from the dirt. Shadow of Mordor is much weaker on that, I played it after shadow of war, and I didn’t get any death cheats, but that might be because I knew the game died less and etc, but it s older and has much less mechanics. Try shadow of war. There is also roguelike dlc, personally it’s okay but not great but some people will have other opinion