This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Gears of War
Gears of War 2. Ever since the war started, Dom has been trying to find his missing wife, Maria. He doesn't get anywhere in the first game, but it's a major plot thread in the second. Dom finally finds Maria, and at first she seems exactly how he remembered. But, as he embraces her she starts to slip out of his hands, Marcus tells him to look again, and it's revealed he was hallucinating. Instead of being his beautiful wife, Maria is now an emaciated, brain-dead shell, reduced to nothing after months of torture. Dom tries to talk her out of it until he realizes the only moral thing he can do is euthanize her himself. Quite possibly the single most powerful, painful, and gut-wrenchingly horrifying moment seen in a video game.
Possibly making it even worse: as Marcus walks away, for just a moment, you can see a flicker of sadness and grief on a face that has before shown nothing but varying degrees of blunt stoicism and quiet rage. If someone as impossibly stone-cold as Marcus Fenix can show grief....
Dom: Marcus! I don't know what to do. I don't know what to do, man! I...
Marcus: Dom. (whispers) It's okay.
Tai's death was also a heartwrencher, especially since everyone thought he was pretty much unkillable, and of course, how it ends. Watching a badass that was second only to Marcus in terms of general badassery blow his brains out with a shotgun...
The rookie in Gears of War 2, Ben Carmine. What else to say? The guy lost his brother Anthony in the first game, gets drafted into the the same squad and exhibits the same impulsive combat behaviour, which greatly concerns Marcus and Dom who still have IdiotHero Anthony's death fresh in memory. Ben stays upbeat along the way, tries to be heroic and live up to the standards of his teammates while Marcus and Dom, familiar with the grim reality of the war, realize things aren't going to end well this time around either. They're right.
What got this troper about Carmine's death was the fact that he died so cheaply, whereas his brother got to go out in a fight. But Anthony was incompetent, whereas Ben was able to hold his own on the field of battle against several waves of Locusts and everything. But instead of going out fighting, he simply wound up getting his insides melted by some giant worm stomach enzymes.
He was disemboweled and nearly torn in half by the Riftworm's immune system. That may actually have been more of a fight than his brother, who was abruptly sniped from about a hundred feet away.
Even worse is how he actually managed to survive plunging several hundred feet into the belly of the monster, and that a few moments sooner Delta might've been able to save him, instead only arriving just as Ben is being disemboweled and vainly fighting to stay alive.
The destruction of Jacinto; humanity has managed to utterly devastate the Locust and wipe out much of the horde, but in doing so sacrificed the one city that truly provided sanctuary for humanity since the start of the war, a desperate act that cost the lives of many survivors and has left them without a home as they flee the collapsing and flooded city, knowing too well of the struggle that lies ahead but not of the new threat that is now emerging.
Well, borderline case perhaps... but just watch the trailers for both games. Just.Watch.
The biggest one of them all in 3 goes to Dom's death, possibly for the entire series as well. He rams a junker into a tank full of Imulsion, parked at a "gas" station uner a leaking Imulsion pipeline, just so Marcus and the others can escape. And just when you think you can hold it in as he sacrifices himself, Gary Jules' Dark Reprise of Mad World by Tears For Fears, which is practically the series' theme song, begins to play. The one character that people never expected to die, actually did. Not to mention the people that grew attached to him after spending all those times in Gears 1 and 2 co-op were affected as well.
Equally heartbreaking is the last conversation that Dom and Marcus ever have.
Marcus: Dom, what the FUCK are you doing?
Dom: I'm pulling the plug on them, Marcus!…Jump, will you? DO IT!
And if that doesn't get you crying, what are Dom's last words?
Dom: Never thought it would end like this, huh? Huh, Maria?
Just before then, Dom kneeling before the stone angel in the graveyard and talking to Maria, then leaving his COG tag around the statue's neck.
Marcus: I just lost my fucking brother! You hear that? My fucking brother!
Marcus has lost friends before, but his reaction to Dom's death is perhaps the most emotional part of the game. The whole idea of the third game is the importance of brotherhood, and seeing Marcus freak out really hits hard. He didn't even react as badly to his father's death.
The entire sequence where Dom dies is one. When Dom is about to crash the tanker and blow up the horde, everyone else jumps off the building and runs to cover... except for Marcus, who just stands there and stares, because he knows what's about to happen and for that moment his mind simply couldn't deal with it. And after the crash, Anya has to damn near hold Marcus in place to keep him from running into the flames to get Dom out, even though he already knows Dom is dead.
Later when Marcus must break the news to Cole and Baird on Azura. The two men are destroyed when they learn of their friend's death; In a rare moment Cole loses all composure and vows revenge on Dom's death; Baird meanwhile is too stunned to even speak, and simply looks away as he processes the reality that Dom is gone.
Adam himself is devastated, having fully expected to see Dom when Marcus made it to the island, and can only offer his condolences when finally reunited with Marcus.
The Stranded themselves qualify, given that most of Char was devastated by Hammer Of Dawn strikes and many people were killed and turned to ash, it's hard to blame them for hating the COG. Griffin is a pretty tragic figure as well, many of the people killed in the strikes were his employees, whom he considered family, and then having the remainder of his people die after being attacked by Myrrah's army(indirectly caused by the main characters), leaving him as the lone survivor in a desolate and decrepit city makes his harsh rant to Marcus a bit more understandable.
The bonus materials in the Limited and Epic editions of the game shed some further light on Marcus and Dom's relationship; a copy of Adam Fenix's Will says that if he dies before Marcus comes of age, guardianship passes to Dom's parents: Marcus and Dom apparently grew up together.
"You ever feel like you're dead, but nobody told you?" One line is all one needs to understand the distance that separates the Augustus Cole of the present from the Cole Train he was at the start of the war. Gears of War is really a game that is best at being quite subtle about the pain its characters endure, and that line sums up everything about Cole so succinctly. A collectible you pick up also reveals that Cole lost his family on E-Day and that he joined the army six days later.
In that same collectible, it says that Cole is joining to fight until the Locust are defeated, but isn't planning to leave Thrashball for good. The horrible implication was that humanity at large probably did believe that the Locust could be defeated without the sort of cost to their population and planet that players know happened because of everything they've seen during the games up to that point. It's the notion that, "We'll beat the Locusts. It'll be tough, but we'll drive them back into their holes, and our lives will go back to how they were," that felt so downright heartbreaking. Cole's line drives the point home: everyone on the planet from before E-Day is dead. The people that they were, even if their physical lives continued, can never be brought back. Too much has been lost for that to happen.
The entire sequence at the Thrashball stadium. Hell all of Cole's lines in 3 were really sad; each whooo, and quip is laboured and forced. He's putting it all on for everybody else's sake, a top notch performance from Lester Speight. While Cole certainly played it up for his fans, with things like the cutout in the supermarket certainly left him shaken, the pure joy during such dark times that the Stranded receive him with, not to mention the sight of his statue still intact at the Stadium, reassures him that legacies survive when ways of life do not.
The death of Adam Fenix, particularly the point where the pulse fires that turns his body into ash, and Marcus is reaching out to hold him one last time.
Even more heartwrenching as the unshakable, emotionless Marcus kneels over his father's ashes; you can actually hear his voice breaking.
When Adam Fenix disintegrates into ash, Marcus just…falls to his knees, completely stunned as Anya exclaims "God!" in the background. Imagine fighting to get back to finding your father again after thinking he was dead for years, realizing that he was proud of you all along, and then he just disappears before your very eyes.
The expression on Marcus' face at the very end as he stares out over the beach. He has literally spent his entire adult life at war, and he has nowhere to go and no idea what to do, especially after both Dom and his father died.
His reaction really serves to spell out the toll the war has taken on humanity; the world's destruction was so complete that you realize that even though they've finally won, it seems as though they truly have lost everything there was to live for.
Quickly becomes heartwarming when Anya goes over to comfort him.
The entire chapter spent in Char. The absolute devestation wrought by the Hammer of Dawn is a powerful sight. The real kicker, though, is the citizens, reduced to statues of ash and frozen in place, all trying and failing to flee from the destruction.