For me it's all stealth.. the ability to mantle/climb structures (within reason.. the Fallout equivalent of vine/moss arrows perhaps) hiding in shadows, camoflage options, speed of movement advantages/disadvantages, Dishonored type weapons Compound/Cross/Wrist bows with a variety of ammo types & the ability to make them. A greater variety of non lethal options, attack elevation/distance considerations, distraction/confusion options (smoke/gas/noise etc) ability to set oil/gas type traps combustable/make enemies slip, fall off ledges etc. The ability to hide in containers & hide bodies (or at least 'clean' them up)