INSTALLATION
Don't use mod managers.

[NEXT-GEN Version]

• Download the main 'Stealth Overhaul' file.
• Copy contents of the main file ('dlc' and 'mods') folders into your 'The Witcher 3 Wild Hunt' main directory.
• Download the 'Next-Gen Patch' file.
• Copy contents of the Patch file ('mods') folder into your 'The Witcher 3 Wild Hunt' main directory, replacing the files
• Open Script Merger, refresh and re-merge any conflicting files
  

[OLD 1.31(2) Version]

• Install the Mod limit fix.
• Download the main 'Stealth Overhaul' file
• Copy contents of the main file ('dlc' and 'mods') folders into your 'The Witcher 3 Wild Hunt' main directory and run Script Merger
  

SNEAKING MECHANIC
How it works:

• Double tap [Witcher Senses] to toggle in or out of stealth. While sneaking you move slower but you can perform a quick dash or a stealth roll by tapping or double tapping [Left Shift] respectively.
  

• [Fast Attack] will backstab humanoid enemies while [Strong Attack] will garotte/decapitate them. Monsters get dismembered instead, regardless of fast or strong attack. A list of valid monster targets can be found at the bottom of the mod description.
  

• You can drag the bodies of human NPCs knocked out or killed by headshots or backstabs by selecting Quen and pressing [Fast attack] or [Strong attack] Indicated by a YELLOW PULSATING ICON
  

When sneaking up on an enemy a RED PULSATING ICON will appear. It indicates that you are within backstabbing distance of a valid target.
This is based on camera angle (60 degrees) and will not show unless your camera is facing your target.
You can reduce the likelihood of getting spotted or busted while in stealth by pressing [Call Horse]. Note that Geralt cannot move while doing this.

CHANGES TO VANILLA WEAPONS AND ABILITIES (WHILE IN STEALTH)

• Bombs will scare and distract humanoid NPC's, causing them to face in the general direction of the explosion and enter a state of blind panic for a few seconds
• Headshots with a crossbow result in an instant kill (as they should)
• Bodyshots will do triple damage while in stealth with all vanilla bolts
• Crossbow bolts will distract NPCs within earshot, causing them to investigate the spot where the bolt landed
• Aard and Igni inflicts triple damage on enemies
• Axii will blind enemies for 5 seconds. Indicated by a WHITE PULSATING ICON
• Quen will cause you perform a non-lethal takedown on human enemies. Indicated by a GREEN PULSATING ICON
  

Additional notes:

• Knocked out NPCs will be unconscious for 30 minutes.
• Knocked out enemies can be finished off by drawing your sword, de-selecting Quen and then pressing [Fast attack] or [Strong attack]. Indicated by a RED PULSATING ICON.
• Axii and Quen features are both cast using [Fast attack] or [Strong attack] while sneaking, NOT [Q].
• Some essential quest NPCs are neutral, which means you can knock them out or backstab them. If you do this you'll lock progress of the quest.
  Don't do this. Or do it - out of spite. Who are we to tell you what to do?
• The drag mechanic has been refined as much as possible given the game's limitations. Dragging bodies down slopes might look wierd and the bodies can't ragdoll due to the engine's limitations. Also, due to the manner in which CDPR derive areas, some NPCs cannot be dragged beyond the borders of their areas. There is nothing we can do about that so you'll just have to deal with it :) 
  

MODIFIED NPC BEHAVIOUR
(Note: "Spotting" refers to enemies seeing you from afar and "Busting" refers to enemies seeing you enough initiate open combat)

This overhaul alters enemy behaviour while you aren't currently sneaking.
If you're busted while sneaking you can escape combat by breaking LOS and staying out of sight for a while before re-entering stealth.
All enemies will notice corpses and will investigate upon discovering them. In addition guardsmen will be wary of suspicious behaviour from individuals (such as sneaking in close proximity of a guardsman's corpse or dragging a body) for some time and will attack anyone who displays such behaviour. Guardsmen will not attack if they bust you sneaking around the corpse of a hostile. Bumping into NPCs will cause them to turn around.

Vision 

• Enemies will not aggro if you stand outside their FOV, meaning they won't magically notice you when you approach unless they actually see you.
• Enemy vision is impacted by environmental factors such as darkness, fog, rain, snow, torch light or whether you're indoors or not.
• Hiding behind bushes or in tall grass is impossible due to the game engine limitations.
• If an enemy spots you they will move to investigate your last know position, giving you a small window of opportunity to disappear from view.
• Opening containers or stealing in close proximity to guards will not get you noticed unless they see you do it. Lighting a torch will get you busted regardless of which way enemies are facing
  

Hearing

• Enemies can hear you if you perform stealth maneuvers or walk/run/sprint while not sneaking in close proximity, for example if you roll right behind an NPC it will turn around to investigate the noise.
• NPCs can hear through floors and walls and will come investigate if they hear anything.
• Guardsmen can no longer hear you drawing your swords while you are sneaking and will not suddenly turn around.
• Casting a sign within earshot will get you busted regardless of which way enemies are facing
• Wearing light armour will make you completely silent while sneaking. Wearing medium and heavy armour has the same audible range as walking.
  

CAT'S CLAW BOLT
A new bolt that gives you the ability to move to otherwise unreachable places via grappling hook. Comes with aim assist system with reticles.

To use it as a grappling hook simply equip it, aim at a surface or ledge and fire. While this bolt's main purpose is mobility it does come with one big combat advantage, the bolt can be used to snare enemies from afar while sneaking. Shooting an enemy that hasn't yet seen you will pull it towards you and stun it for a short time. If you have your sword drawn Geralt will perform an automatic backstab. If an NPC (monsters included) sees another NPC get snared they will walk towards the snared NPC to investigate. In open combat the Cat's Claw works as any other bolt. The bolt's schematic is added to your inventory automatically and can be crafted by amateur blacksmiths or higher.

Reticle aim assist

• Blue reticle = the surface you're currently aiming at can be grappled
• Red reticle = the target you're currently aiming at can be grappled
• Yellow diamond icon = pseudo aim-assist to help with long distance shots. It will tell you that you're right on target
  

The reticles or icon does not appear when using vanilla bolts

IMPORTANT! Using this bolt to traverse obstacles or terrain might make you miss quest triggers or cause them to trigger in the wrong order. This can cause your game to softlock, cause various issues or in some cases crash the game entirely. You might also fall to your death if you grapple sheer drops or steep slopes, so aim carefully and USE WITH CAUTION!!!

VALID MONSTER TARGETS

• Necrophages
• Nekkers
• Beasts (except bears)
• Wild Hunt hounds
  

Note: For logical reasons we decided to exclude any big monsters. Also, while not all monsters can be backstabbed, most monsters can be snuck upon - except vampires and specters. Triple sign and bolt damage applies to the monsters listed above, as does the Axii feature.

MAGIC SPELLS INTEGRATION
Stealth Overhaul has been made to integrate with Magic Spells. When these two mods are used together, some spells take on aspects of Stealth Overhaul.

• Bow of Ardat arrows will distract NPCs the way crossbow bolts do
• Projectile spell impacts will scare NPCs the way bombs do
• Spells deal triple damage if used while in stealth
• Ulcacile spell (invisibility) will get cancelled if you bump into NPCs, provided you aren't using No indignant NPCs mod
  
  Some spells have been restricted from use while in stealth.
  • Sword of Lukatiel (Sword Ring)
  • Sand pillar (Tome of Assassin Bless)
  • Moon Razor (Scroll of Beauty)
  • Radiance (Tome of Carrying)
  • Hybernation (Tome of Permafrost)
  • Harbinger of Death (Tome of Transference)
  • Judgement of Ardent (Grimoire of the Old Gods)
  • Blade of Ulacile (Manuscript of the Clear Horizon)
  • Flame of Dawn (Tome of Meteora)
  • Flame of Winter (Tome of Cold Stars)
    
  Please be aware that if you enter stealth with an active swordbuff or spell, it will get cancelled automatically.
  

KNOWN INCOMPABILITIES

• Devil's Pit mod
• Lazarus (once Laz team finishes their sneak mechanic in the future)
• No indignant NPCs (while not an incompability per se, it disables bumping into NPCs which will render that part of Stealth Overhaul useless
• It seems there are some bugs or glitches between SO behavioural changes and RER enemy NPCs, causing them to not notice you or act otherwise weirdly. This is being currently being looked at, so please be patient
  This list will most likely be updated with more entries in future.
  

If you would like to support my work and keep track of the development process of my mods, kindly consider supporting me on Patreon.

CREDITS AND THANKS

• Sarcenzzz, Traderain, Blumster, rfuzzo and others for developing W3 Modding Tools
• SkacikPL for granting permission to utilize his scripts, thus providing the base of this mod through Devil's Pit mod. Please consider endorsing his mod!
• Munchyfly for various help and teaching Slobadonka the basics of modding so Menschfeind13 didn't have to
• SiriusAmbraj for ideas, pointers and assisting Slobadonka
• X20T3rMiN4t0R for providing essential w2quest assets
• Amasiuncula for various help and motivation
• Nakisa for extensive mod testing and Magic Spells compability testing