If cinematics happen, they happen, but I'm not going to try to force them.
Who said force? They come up naturally in my experience.
In either case their choices are to a) carry on and hope for the best or b) renew their info-gathering efforts and find out why things have changed.
Or just go on in, knowing that between their own creativity and the GM
not being antagonistic, it will likely be interesting and fun.
Ah. I see hit points as an intrinsic property of the creature: if a pirate has ten hit points max when his buddy attacks him he also has ten hit points max when a PC attacks him or when a kitten attacks him or when nobody's attacking him.
4e had foes' mechanical properties change based on who-what was attacking them, which completely blows up internal setting consistency when it comes to game mechanics. The same Ogre (let's call him Bob) would be an Elite if facing a level-1 party and a Minion if facing a level-15 group, where to me Bob is Bob and always has 45 hit points (unless he's taken damage) no matter what and has the same combat capabilties against any foe because that's just who he is.
I don't see a huge problem. To a level 1 party, an ogre is a terrible threat. To a level 15 party, that exact same ogre isn't worth rolling initiative for. 5e gets around that, somewhat, with bounded accuracy and attribute limits and the like, but that hadn't been used yet when 4e was produced.
As we know, hit points aren't supposed to be meat points. They were always supposed to represent something like luck and skill, your ability to dodge oncoming attacks, that what would be a deadly wound to a lesser folk is but a mere scratch to you, that sort of thing. Yes, this kinda falls apart when it comes to things like falling damage, but I view it as your luck running out because you can't dodge the ground (even though in real life, ordinary humans have survived falling out of flying airplanes). By the time you're 15th level, no standard-issue ogre is going to be a threat in combat. That ogre will not be able to dodge out of the way of your blows. They would have to be
very lucky not to die.
Thus, hit points are purely a game mechanic and can safely be ignored when judging how tough someone is. They simply represent how long or difficult it is to kill someone. Something with 100 hit points takes longer or requires harder blows to kill than something with 20 hp. Bob the ogre isn't suddenly weaker when facing a 15th-level party; he just can't stand up to them the same way he can stand up to a 1st-level party.
If it makes you feel better, though, in Daggerheart a minion is a minion is a minion. Adversaries don't change their stats or creature type depending on the level. An ogre remains a Tier 1 Solo no matter what level you are; they'll never become a minion (unless you create a new statblock, at least).
Going in I thought the trap might knock out one or two and-or maaaybe kill one, but a crit-20 is a crit-20 (and crits in our system can get real nasty!) and I don't pull my punches. I seem to recall they'd had chances to notice the trap but either didn't due to bad luck or didn't because they didn't even try; that party were often more concerned with keeping eyes on each other than on anything around them - it was a very knife-in-the-back sort of crew.
Where I'd not trust my own honesty if, having sprung the trap, I then pulled my punch such that less damage was done and fewer or none of them died.
But you wrote the trap in the first place and gave it that much damage (or didn't alter it from a pre-gen module), knowing it
could kill the PCs, and that it had a chance to kill more than one, because you
also created, or approved, the nasty critical system. Thus, you went in being "unfair." Just like bringing in reinforcements is "unfair."
(And I still can't imagine traveling with someone who I don't trust not to backstab me, shared goals notwithstanding--that sounds absolutely hellish. And as a GM, I wouldn't allow such a thing--create a character who will work with the party,
not against them, or go home.)