For months I had been running a D&D 2.0 campaign with 6 players. This had been one of the most complex worlds I had made. I had computer generated maps, detailed 4 major cities and a dozen minor ones. I even had weather patterns and sea currents plotted. My NPC binder was bulging at the seams with wizards, bards, shopkeepers, courtesans, and villains.
The party was recruited to go to several locations, gathering and safeguarding secret items along the way. This was phase one of the larger campaign. The goal was to get the players into the world, let them find out what was going on, who was doing what and where. The first 15 or so levels were fun and some of the best times I remember in gaming.
Then all the items were combined to be this worlds first movable type printer. This was to be the start of phase 2. The device was attacked and destroyed, its mastermind severely wounded and in a mystic comma. My base for phase 2 was to have the players seek out the attackers and save the print master. That is not what happened.
Several players, err PCs expressed happiness that this "Dangerous device had been destroyed." While others did want to go after the attackers, it was because they had been attacked, not to save anyone.
I was a little confused but didn't stress to much because the players were still following the plot hooks. The next game session it got worse. The players had tracked possible connections to a tavern front for a local thieves guild. Note I said "front", I tried to be real clear that the tavern was full of just folks drinking and eating. Lots of merchants and travelers. This was the legal public face of the guild.
It's a bit fuzzy these days, but somewhere in the process of trying to, "rid the world of all knowledge of the evil device..(the printing press)" and get back at the attackers, it was decided to burn down the tavern, ....with everyone in it.
I had always run heroic campaigns, heroes don't burn down taverns full of people. This is where you came in above. As the players described what they were doing I just sat there, stunned. After a bit I blinked, sighed, and said "Please change all your alignments to something evil, thanks for playing, campaign over." I closed my books and folded up my DM screen. My players, some thought I was joking around, some tried to argue what happened as I was putting my dice away.
I had just had a unrecoverable campaign failure.
This was over 15 years ago. thanks to time I can look back objectively at what happened. As a GM I had failed in several things. First I had failed by over prepping. There were hours of work done on NPC's, towns, maps, and plots that were never used.
Second, I failed by presenting a no option plot point. The players should have had more leeway finding out what the object was before phase 2. This would have given me time to adjust the campaign to player expirations.
Third, I failed to know my players well enough. Just because I had always played heroically didn't mean my players had. In fact some of them were early World of Darkness players, far from heroic.
The biggest failure was in myself. I didn't see the signs of GM burn out. There is such a thing as too much of a good thing. Life, demanding job, and family, all can all pile up and press down. Know when to pass the GM screen.