What is, in your opinion, the saddest ending in a video game?

Imo, it's Shin Megami Tensei 2 (It's actually a game that was never localized outside of Japan).

Well, anyway, regardless of which ending you pick, you always have to fight the evil God of the multi-universe who rules over your world.

The God tells you he's going to send your soul to hell and torture you over and over after he smites you. >_>;

So, you fight him, you kill him, and then his voice sounds again telling you that because people still seek out his power in other worlds, he will only be resurrected endlessly and that you killing him didn't really do anything except free the world you live in from his evil grasp (He was threatening to destroy all humans in the planet simply because he doesn't like them). He then places a curse upon you which will last until the end of time.

In the sequel game, assuming you do the bonus dungeon, it's heavily implied the main character of SMT2 is this one character who has a curse placed upon him in which his soul is always reincarnated during the time one of the many planets in the universe dies and he is burdened with writing down the entire history of how the world is changing and what the world's reborn form will be. Apparently, his soul is cursed with traveling among billions of universes in which its time for the end of the world to happen so he can watch and write about it. Worst part is, because he's always reincarnated, he never remembers what he did in his previous life, so he has no idea why he's being cursed in such a way.

Yeah.. >_>;

Honestly, eternal torture, I can't think of anything worse. At least other characters who die get peace at death.

Saddest?

MGS3.

MGS4

Hmm. Probably some of the endings in Silent Hill 2 - clue, the not very happy ones.

I also found Ico to be wonderfully sad, although it depends what you take as its ending point.

SOTC also had a brilliant ending, very moving.

Also, just today I had a sad ending in Left 4 Dead, playing offline for a while due to a borked connection my NPC buddies sadly failed to bother helping me out and let me die, the silly sods. It was a very sad ending indeed.

About MGS:

Regardless of the deaths, those two still chose their path in life so I didn't really find it THAT sad.

Shadow of Colossus? There is no development for the relationship, I had to read the manual to even know that was his sister.

As they said :
Ico
SotC
MGS3
SH2
+
Planescape Torment (well ... the full game is about "regret" in a way ...)
Another World (not really sad ... because there is also hope)

that is all I have for the moment

I'm actually surprised there wasn't a huge amount of posts stating FF7:CC. xD

For some reason, the ending in Super Mario Galaxy brought a few tears into my eyes.

The manual never says it's his sister. It's left almost entirely ambiguous.