I think this was the first time I ever cried with a videogame (Spoilers for the original Starcraft):
I'm not even that much of a PC gamer but after enjoying Age of Empires II, Starcraft just hit the right spot for me. Also, the way Tassadar sacrificed himself for the greater good in combination with the OST is just superb. Even watching it now as an adult it gave me chills.
Though perhaps the saddest and more tragic moment I've ever experienced in a game is probably this (spoilers for the original Fallout):
This one hits me like a ton of bricks every single time I beat the game (which is several since it's my favorite game of all time). I actually didn't even watch it this time, just copied and pasted it here haha.







