"The sad thing is, I was really supporting (the Big Bad) until he killed Trevor. That bastard."
Shannara had THREE particularly nasty Player Punches closer to the end of the game:
1) At the Dragon's Teeth Mountains, you meet with Allanon, your mentor throughout the entire game. After a strangely banal (for Allanon) talk, you have to cross a chasm. Once you do it, "Allanon" starts trying to kill off everyone he can, and is revealed to be the Shifter, disguised in the form of your mentor. If that wasn't sudden enough, he will injure the most lovable character in your party, Shella, to the point of near death. You then have a choice between using the elfstones to heal Shella, or finishing her sufferings by finally killing her with your sword and using the Ritual of Release to save her from becoming Brona's ghost. However, using the elfstones is a Nonstandard Game Over.
2) Just before the last area of the game, the Allanon (the real one) will reveal that the Shifter is STILL ALIVE, despite falling into a near-bottomless chasm. No matter what you do, Davio will do it and die along with the Shifter.
3) A prelude to this is this: Shella and Davio die, Geeka leaves, Telsek leaves, Brendel cannot climb and you're forced to leave him — you enter the final battle alone. Then, you pull out the Sword of Shannara, the "mirror of inner truth". What it actually is, it's a long "dream sequence" where you meet up with Allanon, Brendel, Shella, Davio, and Telsek, not in that order, but I don't remember the real order. Each of them asks one of these hard-to-answer questions (like Shella's "Why did you kill me, Jak?") and you have to choose one of the four answers at the bottom. Despite the fact that you cannot lose, it's one of the most emotionally draining moments of the game.
The Interactive Fiction game Zero Sum Game gives you an adorable sidekick named Maurice. Naturally, he must die in order for the player to win. To be specific, the player has to murder him.
Heavy Rain is made of this. The game is specifically designed to draw you into the character's, making their suffering hit you that much harder. Noteworthy examples include:
Jason's death at the beginning. You know it's coming, and there's nothing you can do about it, but at the same time, you can't help but feel that if you had somehow managed to get there a little faster, you could have saved him. Compounded by the fact that rather than just seeing him in cut-scenes, you've actually played with the child.
Admit it, you winced when you had to make Ethan cut off his own finger.
Some players felt this way when they found out that Shelby is the Origami Killer.
Didn't save Shaun? Great! Now you get to watch Ethan commit suicide (possibly in front of Madison) and, if he's still alive, Norman painfully OD on triptocaine!
The outcome of the epic battle of the Big Robot Bil in The Neverhood:
Willie Trombone: Bil, hang on!
And if that wasn't enough, you can backtrack to the room where Willie was leaving hint messages for you and enjoy reading letters from Klogg, who even bothers to taunt you about Willie getting killed off. Ugh.
The end of Sam & Max: The Devil's Playhouse, when Max goes far beyond No One Could Survive That by exploding in deep space, taking out a few other characters. And then Momma Bosco's Hope Spot sets the player up for a one-two combo. The grueling closing credits give the player plenty of time for that to sink in. (Thankfully, Max from the past arrives in the present using the time machine from Season 2 to replace the dead Max.)
Sal's death was quite heartbreaking too. However, during the post-credits scene, as the camera pans up to the sky, you can see a giant cockroach crawling up a building to the left of the screen, implying that he might have survived (or maybe it was a different cockroach altogether).
In the penultimate episode of Tales of Monkey Island, Lechuck kills Guybrush. The protagonist. And he does so just after Guybrush is starting to believe that Lechuck has made a genuine Heel-Face Turn. And unlike practically everything else in the entire series, it isn't played at all for laughs. It's played entirely straight.
This is the entire point of the classic Interactive Fiction game Photopia. At first the game seems overly linear, but this makes the climax all the more emotionally painful: the player realizes what's about to happen, but no command can stop it, only propel the story forward.
Forced to choose between which companions live? Check!
Forced to mercy kill your own brother after learning he's become a zombie by repeatedly striking him in the head with an axe? Check!
Have to strike at a poor guy's leg in order to cut his foot off to free him from a bear trap before a pack of zombies arrive? Check!
The third chapter delivers a jarring blow to the jaw within its first thirty minutes when Lilly, freefalling into paranoia, kills Carley/Doug. As if it isn't enough that the one killed is Lee's most consistent friend and, especially in Carley's case, well-loved by the fans, there's a good chance that the normally Jerk Ass Lilly will have almost fully warmed up to Lee by just before.
And lastly for Chapter 3... having to Mercy Kill a ten year old boy that you've known since the near beginning of the game because he was bitten by Walkers? CHECK!!
In Chapter 4 ... Lee getting bit by a Walker. Casts a shadow over the entirety of Episode 5, and leads up to a massive Tear Jerker of an ending.