There are now 2 main files. One is for the old 1.30/1.31/1.32 versions of the game and the other is for the next-gen 4.0 update. Download and install the appropriate one for whichever version of the game you are playing.
The easiest way to install is to use the Witcher 3 Mod Manager. It will automatically install the mod and the mod menu for you.
If you prefer to install manually, copy the “modESGO” folder to the “Mods” folder in your Witcher 3 installation directory. Then copy the “bin” folder from inside the “modESGO” folder and paste it into your Witcher 3 installation directory.
If you are using the next-gen version of the game you need to open the "dx12filelist.txt" file (or "dx11filelist.txt" if playing in DirectX 11) in the "Witcher 3 Wild Hunt\bin\config\r4game\user_config_matrix\pc" folder and add "ESGO.xml;" to the end of the list. Do not forget the semicolon at the end. You can also use the mod Menu Filelist Updater to do this for you. If you don't do this step, you will not have a menu for this mod.
If using Nexus Mod Manager, you still need to copy the “bin” folder from inside the “modESGO” folder into your Witcher 3 installation directory. If you don't, you will not see a mod menu in game.
If updating from a previous version, do the same as above. Choose to replace the files when prompted.
If you are using the old 1.30/1.31/1.32 versions of the game, you also need to install the Community Patch - Base mod. This mod was made from it. It helps mod authors so that we only have to release one version of our mods regardless of what game version (Steam, GOG, GOTY, non-GOTY) you have.
If using other mods, please read the Compatibility page.
If the script compiler runs when you start the game, you need to exit the game after reaching the main menu and restart. There is a bug in the vanilla game that can give you -1 potions, bombs, and oils if you load a save after the script compiler runs. This is a vanilla bug and it can happen anytime you add, remove, or update any mods. Better safe than sorry.
Currently ESGO is available in English and is mostly translated to German, Italian, and Russian. If you would like to translate the mod to another language, check the localization folder in the download. All the resources you need and the instructions for how to do it are located there.
Again, the easiest way to uninstall is using the Witcher 3 Mod Manager.
To manually uninstall manually, delete the “modESGO” folder from the “Mods” folder and delete “ESGO.xml” from the “The Witcher 3 Wild Hunt\bin\config\r4game\user_config_matrix\pc” folder.