How to merge mods in Stalker 2

It took less than 24 hours after Stalker 2: Heart of Chornobyl came out for the community to start modding it, which is awesome. Since modders are fiddling about without the modding tools so far, getting multiple mods to behave at once is a process. A merging process.

The challenge of merging mods in Stalker 2

Really, the catch right now lies in the way Unreal Engine 5 manages its mods. Instead of directly replacing or modifying existing baseline configuration files (which is what the majority of STALKER 2‘s mods currently tackle), they are updated during the loading process based on the .pak files you choose to set up.

All Stalker 2 mods go into the ***\Steam\steamapps\common\S.T.A.L.K.E.R. 2 Heart of Chornobyl\Stalker2\Content\Paks\~mods folder, and there’s a fair bit of weirdness present here still. One of the smaller issues, for example, is that all the modded .pak files need to have the ‘_P’ addendum at the end of their file names for them to load.

Unreal Engine 5 override stuff doing its thing, really.

The more problematic part of the equation is that multiple popular mods have to modify the same core game files for them to load correctly, and there’s no way to enforce that without the mod kit. Hence, mod merging.

Merging mods in Stalker 2: Shadow of Chornobyl

I’m not going to lie: having to merge mods is a royal pain. It’s not that the process is difficult once you figure it out, but you will inevitably have to keep doing it as the game and the mods get updates. Presumably (and hopefully!) this will change as GSC Game World rolls out proper mod support, though the team has far more pressing issues to deal with before that.

Now, the meat of the matter: merging mods for STALKER 2 is a three-part process. It consists of mod unpacking, merging, and re-packing. For the purposes of this guide, I’m relying on Stalker_Boss’s appropriately Slav-coded guide video, as featured above. For your reading pleasure, though, I’ve also summarized the important bits below.

How to merge mods for STALKER 2?

The first order of business is getting all the tools you need to make this process a breeze. You should download:

• Notepad++
• BCompare
• RePAK

Note that you’ll need to keep track of the mods’ respective Nexus pages. Most mod creators specify which of the game’s files they edit, so be on the lookout for that piece of information.

Whatever the case may be, the important bit is that both of the clashing mods edit the same file, which is commonly ObjPrototypes.cfg. What this means is that one mod will constantly be attempting to override the other whenever the game loads. This results not in crashes, necessarily, but in one of the mods straight-up not working. Not ideal, obviously.

So, here’s the process that worked for me:

• Create a folder containing all of RePAK’s files, and put your selected .pak mod in that same folder.
• Edit ReUnpak.bat with Notepad++ and add the name of your selected .pak mod at the end of the line.
• Run ReUnpak.bat.
• Repeat the process for your second selected .pak mod.
• Open the unpacked folders to identify exactly which files each .pak modfies.
• Create two folders (1 and 2 are simplest) and place the files that both .pak mods modify in one folder each.
• Open BCompare and select the ‘Text Compare’ option in the central window.
• Choose one overlapping file per BCompare’s window.
• Make note of the small golden arrows on the leftmost side of each file’s reader screen. Clicking on them adds code from one mod into the other, and that’s what you need to do to merge them.
• When you’ve successfully introduced all of one’s .pak mod into the other, click on the window of the mod you’ve been merging into, and hit CTRL+S to save the file.
• Create a new folder to hold your merged game files.
• It’s important that you copy the original unpacked .pak mod’s exact folder structure here. For example, “\Stalker2\Content\GameLite\GameData.”
• Place your modified game files into the GameData folder.
• Create a folder, name it anything you want, and place RePAK and all of the modified files back into it. This also means the files that weren’t overlapping after the unpack.
• Open RePak.bat with Notepad++ and add the name of your modified/merged.pak mod at the end of the line.
• Run RePak.bat.

If you’ve done everything on this list correctly, RePak is going to quickly churn out a merged addon for you to plop back into your ***\Steam\steamapps\common\S.T.A.L.K.E.R. 2 Heart of Chornobyl\Stalker2\Content\Paks\~mods folder. Ideally, it might even work! Do not forget to add ‘_P’ to the end of your .pak mod’s file name, either.

I highly recommend watching Stalker_Boss’s video as well as reading these instructions, mind. Just seeing the process as it unfolds on the video will give you all the context you need to push through the merge, and once you’ve successfully completed one yourself, it won’t be a big deal to do a repeat whenever necessary.

Still a pain, to be sure, but that’s the price you pay if you want to mod a game early! Let’s hope the mod development toolkit is already on the horizon, so merging won’t be necessary in the future.