In terms of the worst session I’ve ever been in, I have two. I’ll start with the one I’d mentioned over at the old forum site.
We had been playing this Pathfinder campaign for more than a dozen sessions, we’re all professional adult males who barely manage to carve out a two-hour session each week to hang out and play. 9PM-11PM Pacific, which for me was midday in Japan while I was working from home and had absolute control over my working hours. A-NY-WAY…
The DM is also working from home and busy enough that he really only wants to run us through a module. He doesn’t improvise much, largely enjoys reading box text and breaking out silly voices for the NPCs. All good.
Oh, hey, I went and found it, so I’ll edit it a bit and drop it here:
The DM was hewing extremely close to the module-as-written, but improvised a barroom brawl during one session. Due to an interesting crit-miss and its consequences, he specified more about a random NPC than intended; our group focused on that NPC.
This was the Pathfinder Swords and Shackles campaign; it starts with the PCs having been press-ganged into service on a pirate ship, all PCs’ initial equipment is held by the quartermaster on the ship, and PCs basically get the shit kicked out of them (or keelhauled) if they step out of line. It’s barbaric, but hey, it’s home.
By this point in the campaign, we were captains of our own pirate ship. Participants in the barroom brawl were locked up by the city guard. We escaped unscathed then went back and bailed the NPC out from jail, with the intent of press-ganging him into service on the ship — the same way our PCs had started the campaign.
We had some parley with the NPC about his belongings, and what we would ransom with the quartermaster. This exposed some improvised backstory, which only made the NPC more interesting to all of us! We were excited to see our DM extend his range, and start filling out the world on his own!
Instead, our DM freaked-the-fuck-out. He claimed that our actions would endanger our alignment, call down our Gods' wrath on us, and maybe get us in dutch with the Pirate Council. We pointed out that this was pretty common pirate practice not just in the Pathfinder world, but in our world as well.
We pointed out that most of us were chaotic neutral. He wasn't having any of it! He seemed cornered. He went on a rant for nearly 3 hours because were interested in a character that he didn't feel comfortable with the repercussions it may have had on the module.
Oddly, if it had been an in-person session, I’m more likely to have stood up and said, “Look, I’ve gotta get home,” and bailed. But because we were online, if we just disconnected, it was likely I’d never speak to the person again, unsure on how to start a conversation after such an epic meltdown.
I've role-played for decades. This was the worst session in which I have ever participated.
In every situation where my players have become interested in a character or organization or object, YES-ANDing has been the way to keep everyone engaged and immersed.