What is the Nemesis system, and why did Warner Bros. patent it?

The Nemesis system is the enemy system Monolith Productions built for Middle-earth: Shadow of Mordor, released by Warner Bros. Interactive Entertainment in September 2014. The game tracks individual Uruk, the orc officers of Sauron's army, once they do something notable, such as killing the player or surviving a fight with him. Tracked Uruk are promoted to captains inside a living hierarchy, with their own names, strengths and weaknesses.

The system runs on memory. An Uruk who survives an encounter remembers it when he meets Talion again. One thrown into a fire may return disfigured and looking for revenge. An Uruk who kills Talion gains power and rises in rank, which cancels the current mission and makes the next meeting harder. Killing captains weakens the army and drops runes for Talion's weapons, and later in the game Talion can brand captains, turn them, and trigger infighting inside the ranks. Deaths were also tracked online, so friends could take Vendetta missions against the Uruk who killed you.

Warner Bros. then patented the system itself. The patent, titled "Nemesis characters, nemesis forts, social vendettas and followers in computer games" and assigned to Warner Bros. Entertainment Inc., covers procedurally generated characters who sit in a hierarchy, remember and react to the player's actions, and change rank, appearance and behaviour because of them. The record shows what a patent does: it gives the holder the right to stop others using the claimed system, or to license it. The sources opened for this page document the grant and that legal effect. They do not include a Warner Bros. press statement explaining the motive, so this page does not invent one.