Validating unity files

Hello,

i am attempting to validate a file upload, the extension that in needs to have is *.unity3d.

I've been attempting multiple ways, and none of them have worked. Do i need to do a custom validation of extension to make it work or?

When i dd the mimetype of my file its: "inode/x-empty"

That, of course, is not enough

None of these work either:

            '' => 'file|required|mimes:application/vnd.unity',
            '' => 'file|required|regex:(unity3d)',
	    '' => 'file|required|mimes:unityweb',
	    '' => 'file|required|mimes:application/octet-stream',

Am i missing something, or do i need to make a seperate manual validation based on extension?