Every once in a while, a DataTime nixie tube clock shows up on fleabay. They are electromechanical, with a complex set of gears driving limit switches to select the tube digits. They have a complete set of indicators for all the world time zones as well. I believe that as you adjust the time zone selector, the hour digits change.
Being driven by a standard AC clock motor, they are probably nicely accurate.
Those always seem to be labeled "Special Edition" as well. I've bid on them a dozen times and have yet to win one.
Now with your clock, I've seen 3 variants of DataTime clocks.
Terry