Additions that have been seen over the past demonstrations of CryEngine 3 include destructible things(such as bullets making actual damage to walls. A simple improvement over CryEngine 2), a better physics engine(grenades make grass and the leaves of trees move when flying past or through them, for example), more realistic character movement(like PCXL-Fan pointed) and (supposedly) it has much better optimizations and improved AI.
Nothing to die for, but if they can actually include all that(and more), then we could see a true competitor for the Unreal and Source engines.
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