Right isn’t an, You just haven’t built the Game Binaries that all just follow these instructions then you should be alright…
Build the “Development Editor Win64”
Build the “DebugGame Win64”
Rename the “UE4Game-Win64-DebugGame.target.xml” in Engine/Build/Receipts to “UE4Game-Win64-Development.target.xml”
Opened HairWorks sample in the Editor then File-> Package Product -> Windows -> 64-bit
EDIT: Then just clarify when packaged that the HairWorks DLL is in Engine/Binaries/ThirdParty/HairWorks/GFSDK_HairWorks.win64.dll for the packaged game if not please copy it manually from the UE4 Source