I agree Demon's Souls is not difficult after you learn. While enemies in Demon's Souls have scripts, they are usually based on the environment situation. For example, if you are facing an NPC black phantom, they will simply hack and slash you. If you have your back to an NPC black phantom, they will back stab you. I only play a few games a year and the Souls series is the closest I know of to Hulan's description. No other current moderately-popular game has the difficult reputation that Souls games do even though their difficulty is only because of trial and error. Maybe there's some niche game or something that fits Hulan's description but are there any popular modern games that closely fit Hulan's description?
