Mine is a cliche these days, to the point where I don't even feel the need to spoiler it - Aeris in
Final Fantasy VII.
I've said this on here before but anyway, in the UK, we didn't get many JRPGs on consoles. FF7 was a
really big deal here because it was the first big JRPG that a publisher threw their weight behind. It was extremely popular; it was the first big JRPG I ever played (I think) and this is the case for many UK gamers, even among those who like myself were already old enough to drink by the turn of the millennium.
Consequently FFVII was the first game in which I
really got invested in its story, and, critically, it was the first game I'd ever encountered where a main character could genuinely die. As you can imagine, this was a bit of a revelation; you'd really got to know this person, you'd spent time equipping, levelling and improving her, but now she was dead and she wasn't going to come back.
You get people on YouTube who say they went through stages of grief over it, or that they actually wept; I'm not going to criticise those people because it's kinda nice that the game was able to move them so much, though personally I didn't go through anything like that. It was more surprise - I was astounded that the game would "go there".
i've been watching anime since i was 9 or 10, and i used to be stone cold about deaths. never cried or anything. but then, as i got older, i started becoming a more emotional person, actually laughing at humorous scenes and crying at just about every emotional one. it doesn't take much these days to fire up the waterworks.
I also experienced this; emotional scenes in movies etc. didn't really faze me once I'd reached adolescence, and that continued until my early 20s; however, since then I've found myself increasingly moved by movies, games (art in general really). I'm not sure if it's a life experience thing; like having more real-life experiences to draw from makes you more empathetic with fictional ones.