There will be spoilers for the game and the DLC in my text and the comments
If you don’t want to be spoiled, play the game first, it’s a really really nice game that’s best when discovered
My favourite moment for the game (as for most players), was when I fetched the Warp Core and had to go to the Nomai Ship. The music made my heart beat so much, and the trip seemed so friggin long.
But my best discovery within the game is understanding how simply turning off the flashlight would be enough to make the quantum objects move. It was so satisfying discovering it for the first time.
I think the thing that got the biggest reaction out of me was in the DLC when you figure out how to bypass the bell alarm.
spoiler
Having to burn yourself alive made my skin crawl and then walking in front of the statues and not hearing the bell, being confused for a moment, then realizing that a corpse can’t hear was chilling.
I agree, it’s quite an experience to have to do that. And just imagine doing it to yourself, or imagining what the owls of the world felt like.