I keep thinking about that too, as I found a few hundred of these tubes. The case design is very challenging, to make it appear reasonably thin, like the watch in the game Metro: Last Light.
It's not exactly unique, as I have made over a thousand similar Nixie watches for over ten years. But it is the only one just like it.
These are IN-16 Nixie tubes. There is a high voltage power supply on the circuit board to make 200V. Did you not see that?