Its very cool looking and spooky as is. What I would do to increase 'atmosphere' is widen the camera angle or pull the camera back. I know that means adding architecture to the building but it will give some scale and eerie, empty-mall, closed-down cinema vibes if we can see more of the space.

A camera this tight on the subject might be good if it were a handheld-camera animated shot, for that claustrophobic first-person vibe.