I don't know if Ubisoft has already worked on this but I have a few ideas to make them game good such as when you kill an enemy you can booby trap it with explosives that can be tripped by the enemy or lured into a kill-zone. And the camouflage should not be just for the muddy ground but in other ways like hiding in trees etc take a look at the Rambo films a you might find a few ideas from that. I hope you take a look at this Ubisoft thanks