Subnautica; at the beginning your pod drops into the surface of the ocean, then you open the hatch and you climb out... to see an infinite expanse of blue sea under a blue sky.
That triggered so many memories for me, I had to take a minute. The color grading on that scene was on point.
One of the Quake games has a section where you get captured, then put on a conveyor belt where you see other people in front of you get mutilated, then that happens to you. That scene almost triggered a dissociative episode.
The original ending of Mass Effect 3 brought me to tears because the Clint Mansell music meshed so well with the on-screen segments, it really moved me. That said I also like the remastered ending; the latter is like the last few chapters of Lord Of The Rings, the former is like an American movie ending.