I made a little game just for test and try to package it but, when I run the packaged game, the graphic is weird or bug.
The scene blink between correct graphic and bugged graphic. I tried to run standalone in the editor but I have the same problem. However, when I run with selected viewport, it run normally.
This is beautiful! So I’m guessing, the head is missing here? Try checking all skeletons and skeletal meshes of your character and make sure they are properly fixed.