Baldur's Gate 3 might be the new king of RPG attention to detail, as well as champion of the sentiment, "Well, well, well, if it isn't the consequences of my own actions." Case and point: there's a hidden game over scene for losing a late game plot critical item, one Larian went out of its way to keep you from misplacing. Spoilers up to the beginning of Act 3 ahead.
Baldur's Gate 3's final act sees you collecting the three Netherstones required to bring the gussied-up Mind Flayer hivemind, the Absolute, to heel. You've really got no incentive to lose them from your inventory, but you can drop them or leave them in containers. They'll always be waiting for your return, however, and you critically can't use the "throw" action on a Netherstone, preventing you from, say, tossing one into a bottomless chasm.
YouTuber BOB_BestOfBugs, however, realized that there's nothing stopping you from putting a Netherstone into a container like a crate or a sack (crucial to the Shadowboxing speedrun tech) and then getting rid of that container. I was able to replicate the trick in my own game, but curiously I only got the game over on losing my second Netherstone, so watch out for potentially soft locking yourself here.
What follows is the most luxurious sort of "you messed up, big time" scene you could possibly ask for, shades of firing a mining laser that wipes out all of humanity in System Shock and its remake.
Your Prism brain buddy, The Emperor, admonishes you for throwing away your one chance at victory, and you're very quickly teleported to the Absolute's extra-planar court where it turns you and your party into Mind Flayers, followed by a big fat game over and the accompanying text, "You've succumbed to Her, now part of the Grand Design…"
I absolutely love this. It's the sort of intricate attention to detail and sense of humor that really sets Baldur's Gate 3 apart from other RPGs. That sensibility is what let all my friends miss major characters, play the game completely wrong (as far as I was concerned), and just keep chugging.
It wouldn't have been surprising if Baldur's Gate 3 instead hit you with a "don't think that's a good idea" bark and refused to let you throw away a plot-critical item, but I love that Larian went the extra mile to make the story respond to player self-sabotage. I have to wonder if there are even more hidden scenes and game overs waiting to be found, and what audacious players will have to do to see them.