Play Report: Operation Unfathomable

I ran Operation Unfathomable and it fell a bit flat.

The other night our regular DM was out of town so we had some friends over to play my homebrew game instead of type VI D&D.  I decided to run Operation Unfathomable.  I backed the kickstarter and have the preview pdf (I actually went in for the combo OU and Odious Uplands which I think is going to take awhile).  I did an hour or so of prep, making bullet points of some of the early descriptions, printing out the intro, the map and Oothu the henchman's stats.  Giving them the list of items to choose.  It all started well.  Having the illustrations to show was great.  But the play itself devolved into a routine of, "Well, we just go forward again."  They ignored side-passages, slew the Mind Bats, and encountered a segmented giant who confiscated the Battle Axe of Spell Cleaving.   Finally they spoke to a Null Priest about the party being held for the Worm Sultan.
I certainly didn't have the whole thing in my head as well as I would have liked and working from a PDF didn't help, but I think there was also a bit a situation where the gonzo-ness was layered on so thick the players weren't sure how to react.  I meant to run a dungeon crawl, but it ended up feeling a bit like the Tomb of Annihilation jungle crawl we've been playing, where it's hard to feel like you are making a meaningful decision because each one leads you so far astray.
I can see Operation Unfathomable working as a really fun romp with the right group of people, it has amazing potential, but I think I would have done better in this case to offer a more traditional style dungeon like Barrowmaze or some such.
I wonder what other peoples' experiences have been like with Operation Unfathomable.  Has anyone else besides the creator DM'd it yet?

Barrowmaze #33-35: Doom of a Death Knight, to Rescue a Barmaid, and the Search for the Pit of Chaos

Nearly lost in the mists of time, a bleary-eyed hobbit recounts the Raven Company's recent weeks of adventure.

#33:  Doom of a Death Knight
A second foray into the flooded tunnel beneath the mysterious black pool behind the bronze door of Nergal in the northern edge of the Barrowmounds saw the wet and bedraggled group exploring the crypts and burial alcoves of the Deserted Dormitory.
The light of the Fount of Law seemed to be dimmed somewhat, but focused more than ever, it's light turning always to the north and east, so they explored that direction, ransacking the bones and treasures as they went.
They were haunted by the echo of booted footsteps.  Whispers of the dead told of the Death Knight Dhekeon the Betrayer searched the halls to return the Fount of Law to it's hidden place.  After some hide and seek the company engaged the Death Knight and his skeletal minions in battle.  In desperation they fled through the chamber of the Water Weird, hoping to turn the two upon each other.  It worked!  Combined with an inspiring potion of heroism, Dhekeon the Betrayer was defeated!

#34: Rescue the Barmaid!
Back in the village of Helix, there was much activity.  Word had gone far and wide that the dead were walking beyond the mounds, leaving treasures unguarded within.  The Duke's son and marshall at arms were organizing the construction of a wooden palisade around the village.  Loggers struggled to pull felled trees from the fringes of the Dolmenwood.
The barmaid Merde had in recent weeks confessed to her involvement in the Cult of Orcus, due to the secret machinations of the false priest Gamdar.  Gamdar had some sort of hold over her soul and compelled her to travel to a glade within the Dolmenwood each month to participate in a ritual of bloodletting.  The Company resolved to accompany her on her journey.  There they laid in ambush, assaulting the Acolyte of Orcus and his goatheaded minions, rescuing the barmaid and taking Gamdar prisoner.
Gamdar told tales of the Acolytes of Orcus searching the Barrowmaze for the lost spark of Nergal, challenging the competing interests of the Necromancers of Set, who he suspected of having their own secret entrance into the maze.
Further, it was rumored that a great and powerful evil lurked in the eastern reaches of the maze, far beyond what had so far been explored.  An evil said to guard the Tablets of Chaos, the hidden word of Nergal Himself.


#35: Search for the Pit of Chaos
Returning to the dungeon, driven by the fading light of the Fount of Law, the Company chose to enter via the mound of the Forgotten King.  Below they encountered a Necromancer of Set with his retinue, who spoke of the power of his superiors but warily backed away from conflict. 
Surging north, the Company edged around a few previously discovered pits, battled blood thirsty spiders and carnivorous flies, and discovered a secret door into a long hall going north.  Torchlight revealed a red blob quivering and smelling of a butcher shop.  Grack ran forward to attack and fell into a bottomless pit... or is it?