Custom Animations#

This guide walks you through the complete process of acquiring animation packs from Fab, adapting them for the standard HELIX character rig, and packaging them as an Addon for the Creator Hub using the Creator Kit.

The process for adapting animations differs depending on whether the asset pack was designed for the older Unreal Engine 4 skeleton or the modern Unreal Engine 5 rig. This guide covers both scenarios.

1. Acquiring & Importing Marketplace Assets#

First, you need to get your animation assets from the marketplace and add them to the Creator Kit project.

Acquire your desired animation pack from Fab (formerly the Unreal Marketplace).
Open the Epic Games Launcher and navigate to the Unreal Engine -> Library tab.
Locate your newly acquired pack in the Fab Library section and click Add To Project.
From the project list, select CreatorKit.

2. Setting Up Your HELIX Addon Package#

Next, you will use the HELIX Packaging Tool to create a dedicated folder for your new addon.

Launch the Creator Kit editor.
Access the HELIX Packaging Tool from the main toolbar.
In the packaging tool window, click New Package.
Enter a unique Package Name (e.g., MyFirstAnimationPack).
Select Addon as the Package Type.
Click Add New Package. This action creates a dedicated folder for your assets (e.g., Content/Addon_MyFirstAnimationPack).
In the Content Browser, locate the main folder for the animation assets you imported in Section 1.

3. Adapting Animations For The HELIX Rig#

This is the most critical step. The method you use depends on the skeleton the asset pack was built for. Follow the section that matches your asset pack.

Option A: For UE5 Rig-Based Packs (Replace Skeleton)#

This is the simpler method, used for modern packs that are already compatible with the UE5 skeleton.

Select all the Animation Sequence assets you wish to package.
Right-click the selection and choose Replace Skeleton...
In the dialog, select SK_Unified from the list. This is the primary skeleton used by default for HELIX characters. Click OK.
Verify that the selected animations now reference the SK_Unified skeleton. Save all modified assets (Ctrl+ShiftS).
In the Content Browser, move all the modified animation assets into your package folder (e.g., Content/Addon_MyFirstAnimationPack).

Option B: For `UE4` or Custom Rig-Based Packs (Retarget Animation)#

This method is for older packs built for the UE4 Mannequin or packs using a custom rig. It uses the IK Retargeting system to create new, compatible animations.

Select all the Animation Sequence assets you wish to package.
Right-click the selection and choose Retarget Animation Assets -> Duplicate and Retarget Animation Assets.
The Animation Retargeting window will open.
For Source Skeleton, select the original skeleton from the downloaded pack (e.g., SK_Mannequin).
For Target Skeleton, choose SKM_Manny located in Content/Characters/Heroes/Unified/.

Note: Your project may contain multiple assets named SKM_Manny. Ensure you select the one from the Unified folder, as shown in the screenshot. This is the mesh associated with our SK_Unified skeleton.
You can typically leave Generate Auto Retargeter checked to automatically map bones. For advanced use cases where the automatic mapping is incorrect, you can uncheck this and provide your own custom IK Rig and IK Retargeter assets.
Review the list of animations to be generated. You can uncheck any you don't need. Click Export Animations button.
On the new window, select your helix package folder (e.g., Content/Addon_MyFirstAnimationPack) as the destination. Click Export.
Click Export button again in next window.
The engine will now process and retarget all selected animations, creating new copies in your package folder that are compatible with the HELIX skeleton.

4. Finalizing and Cooking The Package#

With your animations successfully adapted and moved to your package folder, you can make final adjustments and "cook" the final .pak file.

Open the animation assets inside your package folder (e.g., Content/Addon_MyFirstAnimationPack).
Perform any necessary final adjustments. This is a good time to:
- Enable/Disable Root Motion.
- Add Animation Notifies (AnimNotifies) for events like footsteps or impacts.
- Add or modify Animation Curves.
- Adjust play rate or other settings.
Return to the HELIX Packaging Tool window.
With your package selected, click the Package button. This process will cook your assets into the final .pak file format required by the Creator Hub. This may take some time.
Once cooking is complete, a file explorer window will automatically open, displaying your final .pak file. Your animation pack is now ready to be uploaded to the Creator Hub!

5. (Bonus) Importing Animations From Mixamo#

It's also possible to download animations from Mixamo.com and import them into Creator Kit for packaging with same retargeting steps done for UE4 rig-based packs.

Find an animation you'd like to use from Mixamo and use Y-Bot as your character for best retargeting results.
Click Download button after tweaking your animation.
On the new window, select options as shown on the image below and click Download button. This will download an .fbx file, ready to be imported into Creator Kit.
Create a temporary folder in Creator Kit project, and click Import in content browser to import your mixamo animation .fbx file.
This will import character mesh, materials and animation sequence asset into the target folder.
Follow the same steps starting from Option B: For UE4 Rig-Based Packs (Retarget Animation) section for your imported animation sequence. While retargeting, make sure source & target skeletal meshes are selected correctly. Source mesh should be the skeletal mesh imported from your .fbx file in that case, as shown on the image below.

6. Using Packaged Custom Animations In Worlds#

1. By Lua#

For this example use case, we will try to load our packaged custom animation sequence asset and play it on player character with a Lua script.

After creating your workspace, open build mode and import the package you created in Creator Kit HELIX Packaging Tool. To do that, click File -> Load Package from top bar, navigate to your package folder cooked by Creator Kit, and select configFile.json in the folder.
After import is completed, you will get a panel on the left side of window with the package's name. It might appear empty if your package doesn't have any world placeable assets, which is not a problem.
Now we need to write our Lua script to access the assets inside this package. Click Edit Scripts button and open your workspace folder.

To play an animation with Animation API after a player is spawned, add the server lua script below into WORKSPACE_ID/scripts/main/server/main.lua path in your workspace. If the file doesn't exist, create it.

-- Register a function to listen for player joined global event
RegisterServerEvent('PlayerJoined', function(source)
    local MyCharacter = HPlayer:K2_GetPawn()
    local AnimParams = UE.FHelixPlayAnimParams()

    coroutine.resume(
        coroutine.create(function(delayTime)
            UE.UKismetSystemLibrary.Delay(_G.HWorld, delayTime)

            -- Our custom package is named "Addon_MyFirstAnimationPack", and animation sequence asset inside is named "AS_Crying"
            local result = Animation.Play(MyCharacter, '/Game/Addon_MyFirstAnimationPack/AS_Crying.AS_Crying', AnimParams, function() print('Animation Ended') end)
            print('Animation play result: ', result)
        end),
        1.0
    )
end)

Click the Reload button and then the Play button respectively to re-execute your lua scripts in workspace and then get back into play mode.
Observe your character plays the custom animation after a second.

2. By Blueprint#

[examples coming soon]