I ran Sailors on the Starless Sea when I was on vacation for my younger brother, his son, and his son's girlfriend.
Spoilers, Sweetie: Their first time out, they had a near-TPK after encountering the beastmen in the tower. The two survivors had hung about outside the keep; they attempted the fallen tower (killing one in the resultant slide) and the other found the beastman leader (the only survivor on the other side) dumping bodies down the well. I thought, hey, if the beastman leader falls, they can replenish their characters from within the tower! Nope. Not to be. The TPK was complete.
Not to be dismayed, the players made new characters that approached the keep a week later. They avoided the causeway (and thus the new vine horrors created from their fallen) and came up through the collapsed tower. A dwarf noted the revealed passageway, and all but one of the PCs all squeezed in as the door was opened. Poof! No party. After nearly freezing to death, the survivor high-tailed it out of there, and we called it a night.
This was not enough to dismay them. In fact, they quite enjoyed the game. It took two attempts to get together to play again, but they were persistent in their interest. So.
A day from the last disastrous attempt to explore the keep, the survivor and his new team approach. They discover some treasure in the upper works, and then descend. I ruled that, after the first failure, all of the townspeople were taken below, so there is no one hanging in the tower, the upper works beastmen are now gone, and bad things are happening below.
The players ignore the mosiacs and the pool, they find the robes, and, when they get to the Starless Sea, they have only the four PCs with the robes go across to the ziggurat. Now, me, I am preparing for the inevitable wailing and gnashing of teeth that will occur when the cavern floods and everyone left on the shore is drowned. Well, the one 1st level PC left there will get a Luck Check when/if his body is recovered.
But, I needn't have worried. Even taking control of several of the townsfolk being sacrificed doesn't help the players win their battle against the beastmen, the cultists, and the manifest avatar of the Chaos Lord Molan. They had actually guessed correctly about using the censor and incense to subdue the Chaos Leviathan, but now they were toast. There was no great flood. There was no victory. Molan was restored, to plague the world once more.
But it wasn't a TPK, because characters skulked out of the caverns, and they were carrying some pretty good treasure at the time, including a certain magical axe......
Now, you might think that this would be a real disappointment to the players, and that they might turn away from DCC back to their 3.5. And, of course, they will continue to play 3.5. But, they also appreciated losing, and knowing that whatever they walked away with was earned. And, as my brother pointed out, losing now didn't mean that they would never have a chance to oppose M in the future. Nobody was crying because there were consequences to the adventure. Instead, there was some talk about next year's visit, and maybe getting a game going via the Interwebs.
2e and WotC-D&D both train GMs to fudge player failure. As a player, I find this enormously unsatisfying. As a GM, I find it equally unsatisfying. My position is that the best GMs root for the players, but don't force them to win. It's okay to have a TPK or two. It's okay to lose. It's okay for the remaining PCs (if any) to slink away with their tails between their legs.
SotSS indicates that other villagers have tried before the PCs (see the first encounter!), so it is okay if other villagers try after the first group doesn't return.
We had fun, anyway, and I have introduced three new people (living in two US States) to the joys and perils of DCC!
Cathbad the Meek (herbalist Wizard 1): AC 9; 4 hp; S 7, A 7, St 10, P 17, I 13, L 8; Neutral; Club, herbs, 50' rope, 50 cp; -1 to melee attack rolls. Hideous scar.