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In Skyrim, opponents would search for the player character, but in a non-smart way and simply run to the location that they saw or heard something. In Fallout 3, everyone knew instantly where the player character was as soon as the fight started. One difference is how the AI reacts to an undetected opponent. The workings of sneaking in general and the associated perk/skill underwent a steady evolution with each new Bethesda RPG. Certain NPCs are scripted to turn hostile when stealing from them, even if player was not caught and was hidden.All companions have the effects of 4 ranks of Sneak except Curie who is missing all ranks of Sneak as both robot and synth.Dogmeat had a unique rank 5, but this was removed in patch 1.6.Unlike Chameleon armor, the player need not remain still for this effect to work. Note that this can interfere with aiming using non-scoped weaponry, or seeing the Pip-Boy display properly if brought up during that period of time. Rank 5 bestows an effect similar to that of a Stealth Boy or Chameleon armor effect when entering sneak mode, rendering the player, any equipped weaponry, and the Pip-Boy invisible for approximately one second.If it is active then muffle armor mods are unnecessary and sneaking in power armor becomes much easier. Rank 4 seems to completely eliminate the effect of footsteps on detection odds.The trap avoiding bonuses from ranks 2 and 3 also work when not sneaking.Rank 2 applies to all non-trigger-tension traps, such as physical tripwires, bathroom scales wired to grenades, and even laser tripwires on walls.Sneak works very well with Ninja and other perks that increase the sneak attack bonus multiplier.Effects that grant invisibility like the Stealth Boy and the Stealth Boy power armor torso mod.
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