what i meant was that although rune textures haven't been discussed of, other similar (unreal engine) games have been, and the same rules apply to these textures.
basically, ALL game material is under copyright, and can not be used legally without a permission that would clearly state that you can use them.
i personally don't mind if you use them, but i'd still suggest you'd find a workaround and use some other textures - make your own, for example.
happy mapping.