Epic Games Rule

The engine may not be combined with GPL or similar code

Catalog row in Vendor License Rules · Cited

Kind: Restriction
Statement: Unreal Engine EULA section 6(c): the engine may not be combined with code or content under licences such as the GPL or Creative Commons ShareAlike that would change the terms governing it.
Applies when: Combining engine code with copyleft code
Applies to: The engine may not be combined with GPL or similar code