All of the feedback I received from people who play tested version a1 was useful. Thank you to all of you who played my map, and to all of you who told me what you thought about it.
Version a2 was built from scratch. It was easier than altering version a1, because the feedback I received and my resulting design decisions necessitated a lot of changes of dimensions and passages.
I will leave the details of what has changed to the discussion portion of this download, as I intend to write about how I responded to feedback and how it influenced the design.
Versions a2 and a2a were never uploaded to the web site, so I am uploading a2a for history. I'm about to upload a2b.