Oh, there was a sort of 'instant failure point' on the subject of hostage children. You see, we player characters, explicitly strangers to the town, needed to learn WHY the Lich took children hostage from the townsfolk so we could have a non-combat solution. It unfortunately relied on the party forcing reluctant townsfolk to admit to some sort of transgression in the distant past so we could negotiate reparations or something. As players we could tell that was what was going on, but in character our characters were just fumbling around asking the wrong questions of the wrong NPCs (on a timer, no less.. both in game (we had to rescue teh children within a few hours) and out of game (one shot session), and we had to pass the right social skill test with the right NPC. Which we failed.
Not having all day to investigate why lichs kidnap random children, and not wanting to use out of character knowledge like good players, we basically failed the hostage rescue with a single blown social skill roll... made literally within minutes of the kidnapping. Good times. Trying to use divination almost killed our wizard, which I'm not sure is actually a thing that is supposed to happen in D&D, since I prefer fighters myself, but sure. Dispelled force walls only stayed down for a single round before popping back up, tunneling through stone meant creating magic golem hands that could only be eliminated by repairing the wall. I've mentioned the magic fire that was immune to dispelling magic, did I mention the rickety 'no way to avoid a dex saving throw' bridge that was exactly too long for almost all magical solutions (in 5e, which I'll note severely guts the range on magic) except a multi-round fly spell (I will confess having the wizard (20th level) be a very VERY new player did not help here. She didn't even have a ghost of an idea what spells she should have until the game was two hours old...)
It literally took six hours of game time to get through the front door, simply because every option other than walking into the very obvious trap was explicitly barred by inexplicable magic that was immune to even anti-magic. Ooooohhh.. the poison gas that didn't allow saving throws and didn't care if you didn't need to breath? That was fun.
I literally spent the whole night wondering how in the hell 'THAT' (challenge of the moment) was remotely legal in D&D. I'll allow that I don't know everything, especially about the high end (20th level, as I said), but I spent so long frowning in frustration and/or confusion that I actually got a headache from it.
Gah! Stop bringing up memories of that horrible night! I had it all successfully repressed! Ima be in therapy for weeks!!!!