Have you ever been running a campaign, and you're sure that it's on the way to destruction? The kind of story that has no chance to survive, where all you can do is make your time?
I was running a Pathfinder campaign set on a terraformed moon (the Moon, actually), using tech items and inspired by a mix of Norse myth and Thundarr the Barbarian. I was also experimenting with super-science buffs like bestial mutations, genetic memories in injection form, and unique cyber-augmentation. (In addition to playtesting a custom big six to character ability system.)
It was a mess, basically. Given that the characters had become multi-mutated cyberized amalgams, I was anticipating the manure impacting the whirling air mover. My players usually end up doing something that has major repercussions for the game world. This time though, they only managed to eliminate themselves. The final culprit: two classics, splitting the party and attacking an a higher level NPC they were only supposed to talk with.
Any game implosion stories that surprised you, but looking back seem more obvious?
Nope, never got that carried away.
The only time I can recall at the moment is when a friend (drama queen) and our GM (Mr Perfect) secretly came up with an in game plot to have her character raped by the local Mayor and then pit the group against the law. But it all back fired when the group wanted to continue with our save the nation mission and get back to the mayor later possibly fueled by my character NOT wanting to attack the guards (many of whom were her friends) and certainly NOT without hearing the Mayors side of things since he was her former love interest and she didn't think him capable of rape. Coupled by the fact that the drama queen elf had used lies in the past to color events to her liking. Despite the fact that the whole group decided to shelve this her character had angry words with my character and then attacked me. I accidentally killed her with a very well rolled critical hit. And we all decided to take a break from that game indefinitely.