Dynamic NPC behavior
NPC's and creatures in the world have many different behaviors. Not all creatures won't mindlessly run up to you and attack. Shy creatures often choose to flee, and so may outnumbered enemies that otherwise would have been aggressive. NPC's will also travel in groups, where different inviduals have their own designated roles.
Mortal online aims to unique fights even with normal type of NPC's. You have to learn that Minotaur knocks you down if you don't look at him, Domestic Pigs usually stay near their bigger cousins Razorbacks, they are known for their aggressive mind.
These are just fast examples what have been seen from the beta but a lot more to come.