Okay... inspired by this thread, I started playing this level again and I'm almost done now - got all the stuff etc., even got back to the city twice already. However, I haven't found the blue lock, and the guy at the city keeps telling me to 'go back to the excavation site'.
I'm pretty sure I've been to every accessible place in the level several times over - what place am I missing? What is this mysterious ?
I still have a problem, although it's a different one now:
I found the excavation site and the cat statue and got an ending - but, taking a look in the editor, I noticed there seems to exist an entire different ending, as well, and I have absolutely no idea how to get that ending. Any hints, anyone?
Simply don't get the cat statue. It's a weak ending meant for those who didn't get the blue key.