Descent into darkness. The broken stairs

 From the rulebook:

"Laden down with provisions (for who knows if there is food or even drinkable water below?), you start the treacherous descent of the stairs ... As you get lower, the air thickens and breathing becomes more difficult. Black ash floats in the breeze, filling your nostrils and stinging your eyes. You are just about to call for a break, when you hear a loud buzzing noise, first from one direction and then from the other. You ready your weapons, just as the first bloated body comes flitting into view." 

 

The conjurer trips on the stairs and gets wounded. Giant flies approach.

They fight off the first wave of the nasty critters.

Then a thick, black cloud of poison fog envelopes the party, causing several of them (the ones with yellow counters) to miss their activation.

Flies keep coming endlessly, not allowing our heroes to progress. The dog falls down to some flies, while the barbarian manages to reach a treasure with some iron bark powder in it during a brief lull in the fighting.

But they got stuck in the place and could not reach the bottom of the stairs.

 

At the end of the game the party did not reach the bottom of the stairs, failed to spot a corpse with possible information or treasures and did not seal any fly hole, but killed 14 flies. The dog fully recovers and the ranger reaches experience level 3.