Fun fact:
I’ve managed to load (and use) ‘UnityEngine’ and ‘UnityEditor’, run any Unity C# runtime classes inside a Unreal Engine 4 game project without rebuilding UE4 from GitHub; just for fun.
Worked on UE4 downloaded from Launcher too and also ran in Blueprint only projects (without C++ project generated).
Too bad sharing something like that would be completely illegal and UnityTech for sure would put me in jail for doing so; but is crazy that it works 