Witcher Engine Fix

Crash, performance and quality-of-life fixes for The Witcher: Enhanced Edition. A small DLL that the game loads by itself and that corrects specific engine bugs in memory while the game runs. witcher.exe and your saves are never modified.

What it fixes

	What you notice	Default
Crash in big fights	A random crash when a death effect fires after the creature that caused it is already gone.	on
Physics crash in fights	The physics library sometimes freed an object twice and then gave one block of memory to two objects, which crashed the game later in the fight. A second free is now skipped.	on
Attacks stop working in fights	In crowded fights Geralt could get stuck: every click failed (sometimes with a crossed-out sword) and a held charge did nothing, until you took a step. Typically after a charge attack released while the enemy was out of reach. He is now freed at once, at the latest by the next attack you try.	on
Endurance warning	Quality of life: a charged attack costs 25 Endurance (of 40 at the start), and with less the game dropped it without a sign, so a full charge seemed to do nothing. The Endurance bar now blinks red. Optional: a short message such as "Not enough Endurance (19/25)".	on (message off)
Slow load/save menu	With many saves the menu took seconds to open. 531 saves: 14 s → under 1 s.	on
Faster saving and loading	The save checksum is computed 4× faster (a 230 MB save: ~0.33 s → 0.08 s). Identical result, so saves stay compatible with the unmodified game.	on
Faster area loading	The game rebuilt the mipmaps of textures that ship without them (menus, fog of war) on the CPU at every loading screen. They are now built once and kept in a cache, with byte-identical results: about 1 s less per area transition once an area has been visited (menu textures 0.63 s → 0.05 s; the first menu load at startup 0.44 s → 0.07 s).	on
Shorter wait after loading	After a loading screen the game waited for the texture loader in 250 ms steps, sometimes 0.25 s for nothing. It now checks every millisecond.	on
Slow first load/save menu after a PC restart	The first time the menu opened after a restart, every save was opened cold (the antivirus scans each file again): 3.5-6 s with 575 saves instead of ~1 s. The saves are now read once in the background while the game starts.	on
Main thread forced onto CPU core 0	A 2007-era workaround made the game share core 0 with Windows' interrupt work. Windows can now pick a free core.	on
Hair depends on frame rate	Hair damping was applied once per frame, so hair moved differently above 60 FPS. It now behaves as at 60 FPS at any frame rate.	on
Locked door in "The Source"	Chapter III: Dandelion leads you to Alvin's kidnappers, but their door stays locked. The door is now unlocked when the game failed to, also in saves that are already stuck there.	on
Cursor jumps to the top-left	After the mouse has turned the camera (active pause or Shift in the over-the-shoulder camera), the cursor came back in the top-left area at resolutions above 1366x768. It now comes back in the middle of the screen.	on
Cursor disappears in the main menu	With the over-the-shoulder camera, a Shift press in the main menu (also the one in Win+Shift+S), or coming back to the game after the Snipping Tool, hid the cursor, which only came back while Shift was held. The main menu now keeps its cursor.	on
Mod hotkeys dead after Alt+Tab	In exclusive full screen without DXVK, Alt+Tab made the game rebuild its input handling and forget every hotkey a mod had bound (Witcher Speed Toggle's V/B, quick loot on a key other than Space) until a restart. They are bound again after each Alt+Tab, as at startup.	on
Slow return after alt-tab	After alt-tabbing back, the game could take up to a second to react (it finished a one-second background sleep first). It now reacts at once, and still pauses while in the background.	on
Exit game from the pause menu	Quality of life: the pause menu (Esc) gets an "Exit game" button under "Exit to main menu", with the same "Are you sure?" question, so you no longer have to go through the main menu to quit.	on
Quick loot	Quality of life: Space in the loot window presses "Take all". In shops and storage it does nothing; everywhere else it still pauses, as before. The same as the Witcher Quick Loot mod, which can stay installed alongside (it then takes over).	on
Camera in active pause (over-the-shoulder)	Quality of life: in the over-the-shoulder camera, active pause (Space) shows the cursor and only edge scrolling moved the camera. Hold the middle mouse button to turn it with the mouse, as in the other cameras.	on
Borderless window	Quality of life, off by default: Options > Graphics > "Borderless window". With full screen off and the desktop resolution, the game fills the screen without a border and alt-tab is instant, while the cursor, edge camera turn and pause-in-the-background behave as in full screen.	off
Windows key and Print Screen in game	Quality of life: the game blocked the Windows key, so Win+Shift+S, Print Screen to the Snipping Tool and other Windows key combinations did nothing while it was in front. They work now; a Windows key pressed on its own still does not open the Start menu.	on
Continue	Quality of life: with at least one save, the main menu gets a "Continue" button at the top that loads your newest save (by its time, quicksaves and autosaves included). Without saves the menu is unchanged.	on
Skip the intro	Quality of life, off by default: [qol] skip_intro=1 goes straight to the main menu at startup, without the logos and the intro cinematic. Uses the game's own "don't play intro" switch.	off
Longer draw distances	Optional, off by default: [graphics] detail=1 (high) or 2 (ultra) keeps full-detail scenery, creatures and trees, grass, shadows and lights out to 1.5-3× the game's distances, on top of your options menu; 3 (extreme) goes much farther (shadows 180 m, scenery 10×) for fast PCs. No debug mode or console commands needed. Ctrl+F12 in game cycles off/high/ultra/extreme and shows the level on screen, so you can compare. On a modern PC it cost under 0.5 ms per frame (72 FPS held at 4K).	off

Each fix can be switched off on its own. Details for each fix are in docs/fixes/.

The mod's own texts (the "Exit game" button, "Borderless window", the Ctrl+F12 message and the Endurance message) follow the game's text language, in all ten languages the game ships: English, Polish, German, French, Spanish, Italian, Russian, Czech, Hungarian and Traditional Chinese. Corrections are welcome (how).

Requirements

• The Witcher: Enhanced Edition, patch 1.5. Tested on Steam 1.5.0.1304 (Windows 11, DXVK).
• GOG: same game build, but not tested yet. Every fix checks the exact game code before it patches anything. On a different build it skips itself and writes that to the log, so the worst case is that a fix does nothing.

Installation

1. Download WitcherEngineFix-<version>.zip from Releases.
2. Extract the System and Data folders into your game folder and merge them with the existing ones, for example: ...\steamapps\common\The Witcher Enhanced Edition\
3. Start the game as usual.

To check that it works, open System\witcher_enginefix.log after starting the game. Each fix should say applied.

File	Purpose
System\dinput8.dll	The engine fix. The game loads it automatically
System\witcher_enginefix.ini	Settings
System\Scripts\enginefix_hook.lua	The load/save menu fix, the "The Source" door fix, the pause menu's "Exit game", "Borderless window" in the options, quick loot, "Continue" and the Endurance message
Data\Override\EngineFix\	The "The Source" door script and the quick loot hotkey script (.ncs), with their sources (.nss)
System\Scripts\testtools.lua	Shared startup loader (see Compatibility)

Configuration

System\witcher_enginefix.ini, 1 = on, 0 = off. Restart the game after a change.

[fixes]
fix1=1   ; crash in big fights (death effect)
fix2=1   ; do not force the main thread onto CPU core 0
fix3=0   ; experimental, leave off
fix4=1   ; load/save menu: do not rewrite save thumbnails that are already up to date
fix5=1   ; faster save checksum
fix6=1   ; hair independent of frame rate
fix7=1   ; read the saves in the background at startup (first load/save menu after a PC restart)
fix8=1   ; area loading: cache the mipmaps the game builds on the CPU
fix9=1   ; shorter wait for the texture loader after a loading screen
fix10=1  ; cursor comes back in the middle of the screen after mouse look, not in the top-left area
fix11=1  ; react at once when coming back to the game after an alt-tab
fix12=1  ; Shift does not hide the cursor in the main menu
fix13=1  ; mod hotkeys keep working after Alt+Tab in exclusive full screen
fix14=1  ; physics: an object freed twice no longer corrupts the physics pools (crash in fights)
fix15=1  ; fights: Geralt no longer gets stuck with every attack failing until he moves

[qol]
ots_pause_mmb_camera=1   ; over-the-shoulder camera: hold the middle mouse button to turn it in active pause
borderless=0             ; borderless window; normally set in Options > Graphics, this line counts until the menu has saved it
quick_loot=1             ; quick loot: the key below presses "Take all" in the loot window
quick_loot_key=SPACE     ; one engine key name; with SPACE it still pauses outside the loot window
skip_intro=0             ; 1 = skip the logos and the intro cinematic at startup
continue_button=1        ; "Continue" at the top of the main menu loads the newest save
windows_key=1            ; Windows key combinations and Print Screen work in game (a lone Windows key still does nothing)
endurance_blink=1        ; the Endurance bar blinks red when an attack fails for lack of Endurance
endurance_message=0      ; 1 = also "Not enough Endurance (have/needed)" in the message line

[graphics]
detail=0   ; longer LOD, grass, shadow and light distances: 0 = the game's own, 1 = high, 2 = ultra, 3 = extreme
hotkey=1   ; Ctrl+F12 in game cycles off/high/ultra/extreme and shows the level on screen (until you quit)

The [debug] section holds diagnostics for development (logging only); leave them off.

Quick loot binds its key with the game's own key macros (saved in System\keybinding.ini). A bound key does nothing else, so with SPACE the mod performs the pause itself outside the loot window; any other key only takes all. Key names: A-Z, 0-9, F1-F12, NUMPAD0-NUMPAD9, INSERT, DELETE, HOME, END, PAGEUP, PAGEDOWN, SPACE, TAB, BACK, RETURN and a few more (full list); no modifiers. A key changed here is unbound on the next start.

Three are switched in System\Scripts\enginefix_hook.lua instead: local ENABLED = false turns off the menu's Lua part, local KIDNAP_DOOR_FIX = false the "The Source" door fix, local PAUSE_EXIT_BUTTON = false the pause menu's "Exit game" button.

Compatibility

• Another dinput8.dll: if your System folder already has a dinput8.dll from another mod, do not overwrite it. Both mods use the same file name, so only one can be loaded. Please open an issue.
• DXVK and texture packs (tested with the AiO texture pack) work alongside it. The area loading cache is keyed on the texture data itself, so changing or removing a texture pack is fine.
• Area loading cache: needs a CPU with SSE4.2 (any CPU since about 2008); without it that fix skips itself and says so in the log. ReShade uses d3d9.dll, not dinput8.dll, so it should too (untested).
• Witcher Speed Toggle and Witcher Quick Loot share System\Scripts\testtools.lua with this mod. All three ship the same loader, so they can be installed in any order. Keep the newest: version 3 (this mod 0.7.1, Speed Toggle 1.2.2, Quick Loot 1.0.3) also binds hotkeys again after "Full screen" or the resolution is changed in the options; this mod's DLL does the same after Alt+Tab in exclusive full screen (from 0.7.2). Older versions of those two put back version 1, which turns this mod's menu and door fixes off, and the log says so (Lua save-list fix: INACTIVE): update them, or copy testtools.lua from this mod back.
• Witcher Quick Loot is no longer needed (this mod does the same), but keeping it is fine: while its quickloot_hook.lua is installed, its hotkey and settings are used and this mod's quick loot stays out of the way. The log says which one is active (qol 4).
• Above 60 FPS: the game is usually capped at 60 FPS because of glitches above it. This mod fixes the known hair cause, but other high-frame-rate problems have not been ruled out yet. If you play above 60 and notice something, please report it.

Uninstall

Delete System\dinput8.dll, System\witcher_enginefix.ini, System\witcher_enginefix*.log, System\Scripts\enginefix_hook.lua and Data\Override\EngineFix. Delete System\Scripts\testtools.lua too, unless Speed Toggle or Quick Loot is installed. Remove the line SPACE runscript ef_lootall from System\keybinding.ini (or the whole file, which only holds key macros), otherwise Space stays without its pause; setting quick_loot=0 and starting the game once does the same. The menu fix keeps a thumbnail cache in %LOCALAPPDATA%\The Witcher\enginefix_thumbs and the area loading fix a texture cache in %LOCALAPPDATA%\The Witcher\enginefix_mips (small: about 10 MB after a handful of areas); both are safe to delete at any time.

Reporting a problem

Open an issue and attach System\witcher_enginefix.log. Say which store version you have (Steam/GOG) and whether you use DXVK or other mods.

For developers

build.bat builds build\dinput8.dll (Visual Studio with the C++ x86 tools). tools\install.ps1 -GamePath <game> installs a build, and tools\package-release.ps1 builds the release zip. How each fix was found, the addresses involved and open leads are in docs/fixes/, docs/research.md and AGENTS.md.

License

MIT. The Witcher is a trademark of CD PROJEKT S.A. This is an unofficial fan mod.