I think what made this scenario not so painful for our group was that the GM made it clear that the monster was out of our league during the first encounter, demonstrated by our complete failure to be able to damage it. We are a regular gaming group and we have never really come across this in the past -- so the guidance was invaluable or we would have had a TPK as we vainly attempted to find a way to overcome it.
"What rhymes with 'fun' and 'gun'?" was absolutely the best advice we could have received.
GMs intending to run this should consider letting their players in on this non-standard tactic or you are going to have a bunch of frustrated and unhappy players crumpling up character sheets.
As it is, it was not so fun for us...but we were scared, as promised by the GM. There were a lot of Scooby Do moments running from said monster...which would have been funnier if our PCs had not all been terrified of getting shredded.
So, not a bad scenario...it just needs a sort of disclaimer that it's okay to deviate from the usual tactics into unknown territory for some players/characters PRIOR to the TPK: Run away.
From a player's point of view, this was probably the scenario I have liked least of those I have played. We played 4 characters at tier 4-5, the arcane spellcaster that ran with us was only a level 3. I felt that the scenario encounters leading up to the final battle were fine if somewhat frustrating. However, the final showdown at the end was far more deadly than I have ever encountered -- so much so that it felt like a no-win situation. Granted, in retrospect we did not prepare as thoroughly as we might have and we did not have six characters to improve our mix, but it seemed that no matter what we could have done, someone was going to die. Based on the linear (railroad) tracks of the adventure, there was no way to work around it.
My suggestion to those who might still play this: bring a big party with a good mix of skills/spells to improve your individual PCs survivability and be prepared for the worst.
Pathfinder Society GM. Starfinder Society GM. 2 posts. 2 reviews. No lists. No wishlists. 26 Organized Play characters. 
