Howabout that light gem, eh?
In some ways, I can see it almost being easier to finish some of these missions than it would be to finish the Thief 2 Gold ones.
Less pressure on those doing it to "get it right".
It looks like all of the missions are based on a collection of real-world events / locations rather than a continuous plotline...
... which means an author could just focus on one mission to their heart's content and use real-world fact-finding to base their details and information on.
Dozens of new props and objects would have to be created, but real-world based objects and textures are much easier to come by than fantasy/scifi ones.
I am just musing. /ignore