Why does this guide exist? Unturned has updated from Unity 5.5 to Unity 2017.4 LTS, which means older .unity3d files will need updating to the new engine version.

To make the update process easier there's a new bundling feature: Master Bundles
Further detailed below, this tool will allow you to export all your bundles at once rather than as individual .unity3d files. I've transitioned all of the vanilla content along with Hawaii and Greece to this new system, and Vilespring was kind enough to transition France.

The primary reasons for this engine upgrade are stability related. 5.5 released back at the end of 2016 prior to Unity's focus on improving stability, whereas 2017.4 will be getting patches for another year. Quite a few longtime bugs are fixed in this new version, and as a result I've been able to clean up some workarounds and improve performance in a few areas. Apple has also decided to deprecate OpenGL support, so it's important to have 2017.4's Metal integration.

Rather than exporting each bundle to an individual .unity3d asset bundle, you can export multiple bundles into a combined .masterbundle. It's more efficient both time and performance wise. Note: You don't have to use masterbundles, it can be easier to iterate using the .unity3d bundles and enable/disable the masterbundle as-needed.

This is really how it should have been from the first place. If the game detects a master bundle file, it will load bundles from sub-directories using their relative folder path. To help explain, here's an example:

MyModBundles / Items / Gun / Gun.dat
If MyModBundles contains a master bundle, it will try to load all of the Unity files using the relative path /Items/Gun. This means it's important for the .dat folders and Unity folders to line up 1:1.


Copy all of the files from Unturned/Bundles/Sources/Tools to YourUnityProject/Assets/Editor. MasterBundleTool will now be available from Window > Unturned.

Most shaders used by the vanilla game are now available as a unity package in Unturned/Bundles/Sources/Complete_Packages/All_Shaders.unitypackage. Using them improves compatibility with the base game content.


Begin by selecting a folder within the Unity Project Browser that contains your bundles, and assigning it to an AssetBundle from the Unity Inspector. Most of the vanilla bundles are in an assetbundle called "core.masterbundle", and map-specific bundles are in assetbundles named like "hawaii.masterbundle" or "france.masterbundle".

Open the Master Bundle Tool and click the Asset Bundles dropdown arrow. You should see the assetbundle you just created listed here. Clicking the checkbox next to its name will flag it as a masterbundle.

Now when click the Master Bundles dropdown arrow you will see your masterbundle listed. Clicking the '...' button will let you select a folder to export the masterbundle into. This will warn you that you need a MasterBundle.dat file which we cover in the next section.

Note that for your masterbundle to be fully compatible with mac and linux you will need to check Multi-platform when exporting a final copy. Previously assetbundles were not properly compatible with those platforms.


Each folder containing a master bundle needs a MasterBundle.dat file. When the game traverses the file hierarchy it will check for a MasterBundle.dat, and if one is present it will assume all sub-folders should be redirected into this master bundle. You can configure these keys in the MasterBundle.dat file:

Asset_Bundle_Name: File name of the windows masterbundle exported from Unity. e.g. greece.masterbundle
Asset_Prefix: Path to the folder you selected as an assetbundle in Unity. Building on the MyModBundles example from earlier, you might use Assets/MyModMasterBundle in which case the game would look for the gun in Assets/MyModMasterBundle/Items/Gun.

There are some keys configurable per-dat as well:

Exclude_From_Master_Bundle: If included this .dat will ignore any parent masterbundles and instead look for an individual .unity3d file.
Master_Bundle_Override: Name of a masterbundle to redirect to, for example core.masterbundle. Useful when using Bundle_Override_Path like for an item with custom stats but uses the vanilla bundle, or a note that uses the vanilla note object.

You can safely upload your updated content to the workshop ahead of time. Players using pre-3.28 versions will receive a message that the workshop version is using a newer Unity build. Conversely, players on the 3.28+ client will receive a message for workshop items that have not yet been updated to the newer version of Unity.

Most likely the Color Space setting in your Unity project needs adjusting. Navigate to Edit > Project Settings > Player. Under the Other Settings section change Color Space to Linear.

If that doesn't work, double-check that sRGB is enabled on your textures.


Materials default to instancing disabled now, so enable the Instancing flag in the Unity material inspector and rebuild the asset bundle.