http://www.pcgamer.com/huge-assassins-creed-origins-patch-targets-performance-and-npc-behaviour-adds-nightmare-mode/

In his review, Chris praised Assassin's Creed Origins' "brilliant" setting and new systems that combine well with the series formula. Naturally, there was room for improvement—which is something today's extensive patch hopes to address. 

Due today, update 1.1.0 introduces a new Nightmare difficulty mode and adds a new NPC scaling option that lets enemies scale up to player's levels. Ubisoft qualifies this by saying enemies will only scale up to meet the player's level as they progress, and will not scale down. A new 'Horde' mode has been added to the Arena, while HDR display is now supported for PC players.