Thank you all for the feedback. 
I am truly happy to see this works out well so far.
That said, we have decided to not make exceptions for Project Skyscraper to be using ‘global pins’. Main reason for some users usually not finding information to get started, is due to unfamiliarity with the forum (Discourse) structure. As long as we provide some guidance here and there, and users take the time to familiarise themselves, it usually works out fine.
I have however gone over the Project Skyscraper - Welcome / Info and restructured it some more. The use of ‘categories’ hopefully being somewhat clearer now, using category links as well.
I have also created a new topic about pins: Pinning / Unpinning of Topics
And a topic about urls / links: Use of urls and forum type links