Hey, no problem :) I slightly remembered/suspected there was an in-game text hint, just wasn't sure. The explanation - in terms of in-game lore - is perfectly fine, I like the fact that you did an extra effort and came up with something that made sense story wise. But here is something that may be worth to consider:

I think in normal cases - during a first walkthrough - players would probably leave the portal shut down when they enter the chamber of the hourglass (since in both cases of f...

Yes, absolutely! Also, I think what makes the pacing really great in this mission is the fact that you have to unlock the different areas one by one - so, it doesn't just throw you all the map at once. Lots of levels go too far with the non-linearity and all the different routes, but Nick's approach here was actually quite clever.

I'm in the same shoes as MarcusFlintlock was - I didn't realize there was this "Say hello!" topic here. But, better late than never I guess :)
I'm a Thief player since 2006 (played Deadly Shadows first, but started to appreciate Thief 1 and 2 much more later on) and one of the many silent critics of fan missions :D
Nice to see the series still has its fan base and lots of talented people put time and effort into often surprisingly well designed fan missions.
Also, congrats and many thanks...