Warner Bros. Interactive has patented their nemesis system used in Shadow of War and Shadow of Mordor to prohibit and prevent use in other games.
Source: WB Games' Nemesis System Patent Was Approved This Week After Multiple Attempts - IGN
For those that don’t know, the Nemesis System is a mechanic which allows you to build truly unique and custom storylines with enemies, AI and more in the game world. Various characteristics, links, ideas, personalities and mentalities/attack strategies are all integrated and ready to be born into enemies through this system.
For example: If you kill Person A, who had a blood brother, the blood brother may seek revenge on you at any random point in the game. If the blood brother had an ambush perk, he would try to kill you when you’re at a disadvantage. If you beat him, he may run and swear to beat you again next time with an even bigger determination and force behind him. If he beats you, he may gain popularity among his gang and get better weapons, status and abilities.
This, in short, fucking sucks. It’s one of the most innovative things in gaming today and Warner Bros. aren’t using it at all, which means it won’t see new innovation, takes or what not. Imagine if Wolfenstein 3-D patented holding multiple weapons at once in an FPS or something? Just straight up shitty.