If you fail to save Cid after The End of the World as We Know It, Celes, having lost everything, decides to climbs a cliff to leap off onto the rocks below (which, according to Cid, all other survivors in the island had done when they succumbed to despair). She survives on a miracle, sees Locke's bandanna wrapped around a pigeon's wing, and regains her will to live.
Shadow does this in his segment of the game's ending if you have him in your party. To sum up his motivations, he'd let a friend die a very painful death instead of finishing him himself and has carried the guilt for years with him. With the world saved, he stays in the collapsing final dungeon to die and join his friend in death. Complete with him telling his dog to go on without him. Tear Jerker, ahoy.
In Final Fantasy VII, When Barret confronts his old friend Dyne, they duke it out. After defeat brings him back to his senses, Dyne realizes the horrible things he's done and tells Barret to keep taking care of Marlene, who was his child by birth, saying his hands are too stained to carry her anymore. Then he drags himself to a cliff and throws himself off it. The game conveniently forgets that he actually survived that same drop years before.
In Camp Sunshine, a survival horror slasher game, the supernatural killer's backstory eventually shows that his father, Jacob, was forced to kill him a couple of years ago when he went on his first murder spree. Jacob was so distraught at this that he killed himself soon afterward.
God of War starts with Kratos throwing himself off a cliff, with the game being a How We Got Here. The Gods decide that You Kill It, You Bought It and therefore promote him as the new God of War. This turns out badly for them when they renege on this decision.
Quite a few people in backstories. Redd White in particular is apparently responsible for a large number of instances of this (as the driver, not the drivee).
Played straight and subverted for different people in Justice For All. When "Prosecutor Miles Edgeworth chooses death", what he really means is that he's taking a sabbatical in Europe to re-evaluate his legal philosophy and doesn't see why Wright is getting so exercised about it. Played straight with Adrian Andrews' mentor Celeste Inpax. She hanged herself two years ago when Juan broke their engagement just because she had once dated his rival, Matt Engarde. And Adrian attempted suicide herself over Celeste's death, but she lived.
Terry Fawles does it onscreen in the courtroom in Trials and Tribulations. His girlfriend Dahlia really messed him up. The same driver of suicide taunts Phoenix in 3-5 by drawing the conclusion that Maya accidentally killed her mother, then killed herself out of sheer guilt. Fortunately, she's proven wrong on both accounts a bit later.
Also happens in the fourth game: not in any of Apollo's cases, but in the flashback segment of 4-4, the supposed murder victim, Magnifi Grammarye, committed suicide once he chose his successor, since he was already dying of cancer.
Happens somewhat often in the Professor Layton vs. Ace Attorney crossover. The alleged murder victim Sir Newton Belduke poisoned himself due to the guilt of knowing the town's dark secret. Years before, his butler and adopted daughter Jean tried drowning herself after appearing to have accidentally killed her pet goat with magic. In addition, Espella is convinced that she's really the Great Witch who burned down the city 100 years ago, and tries to have herself executed in a witch trial. In reality, the fire was 12 years ago and her father faked the existence of witches to try to convince her that it wasn't her fault. When this is revealed, she tries to throw herself off the bell tower.
Joshua, supposedly. He's likely to be lying, but if it was suicide it didn't occur recently.
It's implied somewhat that Shiki committed suicide too.
In the Visual NovelHeart de Roommate, the gang attempt to befriend a rather lonely schoolgirl with a past history of attempted suicide. This leads to one of the darkest scenes in the game, when during a conversation with the main character on the roof she accuses him of only being interested because he fancies her and offers to have sex with him if he'll leave her alone. When he refuses she proceeds to make another offer... sleep with her or she'll scream that he's a rapist and jump off the roof, something that seems quite plausible given her past history and self destructive personality. She doesn't go through with it no matter what the player chooses, though accepting her offer leads to a rather bleak Non-Standard Game Over.
Drakengard has two examples. The first one is Leonard, who comes home to see his family dead and his home razed by the evil Empire. Feeling that he has failed to protect them, he gets very close to cutting his own throat, only being stopped by a malicious fairy. The second is the protagonist's sister, who, due to Mind Rape and her brother being disgusted by her incestuous feelings for him, commits suicide to escape disgrace.
One of the bad endings in School Days has this too: Kotonoha Katsura, the Ojou of the story, throws herself off a building if Makoto (in the main player's shoes) goes with Sekai instead. And she actually dies in front of Sekai and Makoto (High-Pressure Blood and all), traumatising them so badly that Makoto not only breaks up with Sekai, but swears off romanceforever.
Dr. Janice Polito was driven to suicide when she found out that she unleashed SHODAN. You find her corpse in her office, and her suicide note in the Rickenbacker church.
A "ghost" crew member snaps under the horror of what's happening, says sorry to his wife and children, and shoots himself. Several corpses are found sitting with a gun in their hands, implying they've chosen the same way out.
In the end of Super Robot Wars Original Generation 2 (and Advance too), being the 'only survivor' of the Shadow Mirror, Lamia Loveless thought that she has failed her mission, killed her teammates and superiors, and is a defective product all around, and thus she attempts to self destruct... only to be stopped by her new teammates just in time and be persuaded to live her life in the current world. She actually has more self-destruct attempts throughout the series, but only this occasion fits the trope.
Starcraft: Gerard DuGalle commits suicide after his defeat, in remorse over his gullibility and murder of Alexei Stukov.
Super Fire Pro Wrestling Special featured a story where, about halfway through, things get worse, and worse, and worse... First, you suffer a string of defeats. Then, your coach winds up dead. Then, you accidentally kill your opponent in one match. Then, your girlfriend leaves you. Then, your opponent for the championship, a Ric FlairExpy, kills your tag-team partner AND reveals that he was the one who killed your coach. Once you defeat the murderer and take the championship for your own, though, the hero realizes that it really is lonely at the top. He shoots himself in the head three days later. Would it be any surprise that this particular game's story was written by a rookie Suda51?
Yume Nikki: After dropping the 24 effects off in the Nexus, Madotsuki wakes up from her dream, walks out onto the balcony... and leaps off the edge. Cut to black and a bloody red smear on the canvas.
In Illusion of Gaia - Will is forced into a game of Russian Roulette using a poisoned drink. Will's psychic powers allow him him to dodge the poison, but the other player, Straw Hat, drinks the poisoned shot anyway, out of sheer wounded pride. After this, you read a letter from him telling you he had a terminal disease and was playing the Russian Glass Game so that his pregnant wife would be finacially secure after his death. He had nothing to lose by drinking the poison.
Rivet City has Mister Lopez, a suicidal senior whose family was killed by Raiders, standing at the top of the Bridge Tower. You can either convince him to jump to his death (bad Karma), or talk him out of it (good Karma).
Rivet City also has Mei Wong, an escaped slave. She's terrified of a man named Sister who's a former slaver and thinks he's coming after her. You can either give her money to buy a gun for protection (good Karma), or tell Sister (who doesn't really care) she's a slave and let Mei know you told him, causing her to overreact and kill herself (bad Karma).
In the Fallout 3 add-on "Operation Anchorage", if you have a high enough level in Speech you can prompt General Jingwei to commit suicide by falling on his own sword, after he decides he would rather die than be captured.
You can sometimes come across skeletal remains with bloodstains caked into the walls and guns lying next to them. Presumably when the nuclear holocaust happened, some people decided to die on their own terms.
If you tell Ranger Chief Hanlon that you know he's the one behind the bizarre intelligence reports to get the Rangers out of what he considers a Hopeless War, he'll excuse himself, announce his misdeeds to Camp Golf, and shoot himself in the head.
Captain Curtis, a Legion mole in Camp McCarran, also kills himself after you report him to Colonel Hsu, providing you didn't kill him yourself.
In the Dead Money DLC, when the security came on-line at the Sierra Madre Casino, some of the guests killed themselves to avoid dying of starvation or being killed by security. This was the ultimate fate of Vera Keyes, the singer for whom the casino was built.
If General Oliver was talked down in the House ending, Mr. House will state that Oliver has a roughly 40% chance of committing suicide since he'll be publicly disgraced and held responsible for losing the war once he returns to NCR territory, with his hopes of pursuing a political career dashed to the ground. The same probably applies in the Independent Vegas ending.
If you turn Arcade Gannon into a slave for Caesar's Legion, and win the game for the Legion, the ending narration says that after years of unwilling servitude, he saw an opportunity to off himself when nobody was looking and took it, disemboweling himself with a surgical scalpel. Since he was the Legion's only doctor (which is why they wanted him as a slave in the first place), they weren't able to save him.
Near the end of Dead Money, Dog decides to kill himself to stop his Split Personality from constantly nagging him. Unfortunately, his method involves blowing himself up and taking the whole Sierra Madre Casino with him. You must stealthily turn off the three gas valves in the area and then talk to him, at which point you can either convince him to kill himself by snapping his own neck instead, cause either personality to do a Split-Personality Takeover, or cause a Split-Personality Merge. If you don't have the Speech skill for any of that, you will have to fight him and kill him yourself.
If you convince Boone to become vengeful over the events at Bitter Springs and win the game for the NCR, the ending narration says that Boone went back to California to track down the officer who ordered the Bitter Springs attack, and brought along a pistol loaded with only two bullets. If you make him vengeful but win the game for the Legion, the ending says that Boone committed Suicide by Cop, recklessly slaughtering as many Legionaries as he could until he was inevitably captured and crucified.
In Metal Gear Solid 2, it is revealed that Otacon's father drowned himself after finding out that his wife (Otacon's step-mother) and son were having an affair. In the same game, Fortune's mother committed suicide after her husband's death and her son-in-law's imprisonment.
In Metal Gear Solid 3, it's implied that the reason why the Cobra Unit was still utilizing their microbombs essentially dealt with this trope.
In Metal Gear Solid 4, Vamp and Naomi go out this way after disabling the nanomachines keeping them alive.
In ObsCure II, one of the playable characters commits suicide after his girlfriend, and most of his friends have been killed in the 'incident' at the school. (By incident we mean the survival horror plot.) The sequel is Darker and Edgier than the original, which is no small feat seeing as in the first game everyone dies in horrible experiments except for the playable characters.
One popular backstory of the Touhou character Yuyuko Saigyouji is her committing suicide after learning about her power evolving from controlling dead spirits into invoking the death of anything. Fortunately (?) Yukari ensured her spirit could never "cross over" completely, allowing her to continue existing as a Cute Ghost Girl. Many popular Yuyuko/Yukari fan works have the two be friends, or even a couple, back when Yuyuko was still human. This delves far past Tear Jerker and into soul-crushing territory when you realize Yuyuko doesn't seem to remember anything about her past life, or Yukari. Indeed, some of Yukari's personality characteristics, such as constant sleeping and over-friendliness, are symptoms of depression.
Tai Kaliso in Gears of War 2, after being rescued from Locust torture, is given a shotgun for the purpose of defending himself from the incoming Locust reinforcements. Without a word, he puts it to his chin instead and blows his brains out. One of the comics focuses on Tai's time in captivity, where Tai's narration states that he was tortured so badly that his soul felt the need to escape his body. And since his religion considers a body with no soul to be just a useless empty husk, well...
Not only does Fai Dan shoot himself to escape the Thorian's mind control, but other characters can also be Driven to Suicide depending on the player's decisions, including Saren.
Also a Salarian researcher, who shot himself to escape being ripped apart by the rachni.
Ronald Taylor can be left a pistol with which to kill himself.
In Mass Effect 3, both Tali and Samara can potentially commit suicide. The former if the geth destroy the entire Migrant Fleet, and the latter because she's forced to make a choice between obeying the Justicar Code or killing her daughter.
Like Saren before him, The Illusive Man can also be convinced to kill himself to escape Reaper indoctrination in the Grand Finale.
The third game loves this trope. The characters listed here? That's not even half the number that this can happen to. For understandable reasons.
Clone!Shepard does this in the Paragon Ending of the Citadel DLC, refusing to take Shepard's hand and letting themselves fall from the edge of the Normandy ramp. It's implied that their Despair Event Horizon cames after Shepard's friends rushed to save them from falling, while s/he was callously left to die by Brooks, thus answering their earlier rant "What makes you so damn special?" Shepard has friends.
Shepard: Take my hand, and you can live.
Clone!Shepard: For what?
In the third game, when you meet Dr. Archer of the Ovelord DLC in 2, depending on several factors, including whether or not you've done the Grissom Academy sidequest in time or whether or not you've dealt with the Geth at that point, he'll take out a pistol and walk away so he can end it all.
Archer: God be with you, Commander. He was never with me.
If the Warden sides with Caridin in the "Paragon of Her Kind" quest in Dragon Age: Origins, he gives the Warden a crown before jumping to his death from a high ledge, into a river of lava, to atone for making golemsfrom living dwarves. The same goes for Branka if the Warden sides with her and then convinces her to destroy the Anvil rather than continuing to make golems. Also from that quest Hespith apparently commits suicide offscreen, understandably as she was in the process of being turned into a Broodmother. Zathrian can also be persuaded to end his life—which ends the curse on the werewolves, and frees the Lady of the Forest—in "Nature of the Beast"; it's considered the best ending, being a third option between killing all the werewolves and killing all the elves.
Anders very clearly has a death wish by the end of Dragon Age II, and it is both creepy and heartbreaking.
When Geralt meets the Bloody Baron Philip Strenger in The Witcher 3, he's hired by the Baron to track down his wife and daughter in exchange for information about Ciri. His daughter ran off to join the Church of the Eternal Fire and refuses to return, resenting him for his alcoholism and wife-beating. His wife Anna made a pact with a coven of witches known as the Crones to have them abort her unborn daughter, but in exchange they forced her into slavery and drove her mad. If Geralt saves the children they were going to kill, then the Crones turn Anna into a Water Hag and she dies in front of the Baron and their daughter Tamara. The Baron later hangs himself from the tree in front of their castle.
Setsumi from Narcissu since she had terminal disease, she's going to die anyway, and she doesn't want to die at home or in the hospital.
Archer, AKA Emiya Shirou of Fate/stay night, except as a spirit existing primarily outside of time he's actually incapable of death, so his suicide plan is killing Shirou so that he can't make the contract with the world and become Archer, hopefully canceling himself out of existence. Several characters point out, including himself, that this is very unlikely to work.
Several members of the USG Ishimura crew who already haven't been turned into Necromorphs commit suicide; examples include the man who headbutts a bulkhead until his head is pulped, the woman in the medical bay who severs her throat with a surgical saw, and a woman in Doctor Challus Mercer's evil Unitology Room Full of Crazy who blasts her own head off. Also Isaac's girlfriend Nicole killed herself via lethal injection before the game began; Isaac just doesn't realize it until the end.
And in the sequel, the Unitology cathedral contains groups of dead bodies with plastic bags over their heads and an empty chalice nearby. It's implied that they committed mass suicide so they could be reborn as Necromorphs.
This can also happen to Isaac himself near the end of the second game, if you let Nicole grab him. And, like every other death scene, it's...not pretty, to say the least. He puts himself out with the javelin gun. TO THE HEAD.
At the beginning of the game, for example, several inmates in Cell Block T hang themselves following the earthquake.
In a vision of the past, a military commander shoots himself rather than face a court-martial.
Another flashback reveals that in 1681, three little girls hurled themselves off a cliff after realising that their seemingly harmless prank had resulted in the execution of eleven innocent people. Unfortunately, they don't stay dead.
Hermes Haight, the prison's most infamous executioner, killed himself in the gas chamber; according to his poisonous ghost, this was the final step in a very long obsession with learning what his victims felt.
A heroin addict blows his brains out with a shotgun, apparently unable to "weather the low."
Three inmates in solitary confinement at East Baltimore Correctional committed suicide rather than spend another six months alone in the darkness.
It's revealed that inmate Ranse Truman tried to slit his wrists with a sharpened spoon after spending a few months on Carnate Island and exploring its unique history. When you meet him in the second game, he appears to have tried to cut his throat at some point.
In Robot Alchemic Drive, Nanao kills herself if the building where she works is crushed too many times.
Kind of a fact of life in The Last of Us. Many people in the zombie infected wasteland you encounter choose to kill themselves rather than succumb to the infection. Just a few of these:
At the very beginning you run into a man, who is trapped and his mask is broken, exposing him to spores. He begs you to kill him so he doesn't turn. Whether you grant his request is up to you.
Your partner, Tess, gets infected early on and chooses to die in a blaze of glory, rather than succumb to infection.
You come across Bill's partner, Frank, who killed himself after getting bitten.
Henry kills himself after crossing the despair event horizon once he is forced to kill his infected brother.
Through letters you find in a sewer, you learn the story of a failed colony that got overrun by infected. One of the colonists chose to kill himself and his kids to spare them from a fate worse than death. You find the message "they didn't suffer" carved into the floor near the bodies.
HK-47: Statement: Oh, yes. My master had quite the collection of tortured individuals that seemed unable to confront their basic personality conflicts. Let me cite some specific examples. Mockery: [mimicking Carth's voice] "Oh, master, I do not trust you! I cannot trust you or anyone ever again!" Mockery: [mimicking Bastila's voice] "Oh, master, I love you but I hate all you stand for, but I think we should go press our slimy, mucus-covered lips together in the cargo hold!" Conclusion: Such pheromone-driven responses never cease to decrease the charge in my capacitors and make me wish I could put a blaster pistol to my behavior core and pull the trigger.
If you go bankrupt in Theme Park, the game shows a cutscene of the park owner jumping from a window while a family photograph fades, and Chopin's Funeral March plays. Though it turns out he was actually jumping out of a first-story window, as he turns around, grabs the windowsill, and pulls himself back up. As it was a game for all ages, even joking about suicide was pretty controversial. It even describes what will happen if you go bankrupt in the manual. It's actually pretty creepy; watch at your own risk. The Mega Drive/Genesis version contains only a still image of that scene, which happens to be the park owner in mid jump.
Kohaku in Tsukihime in Hisui's route. The True End she succeeds. The Good End Shiki saves her at the cost of some of his lifespan. Either way, she points out that she has nothing left to live for anymore and did not really want to do what she did.
Erica in the backstory for Malicious, she was weak and frail, the girl was in the middle of a grand scale war started by her own father King Eldrake, the tyrant corrupted his own kingdom and had his wife, Queen Ashlelei, imprisoned. When Erica and her brother freed their mother to start a revolution, Eldrake started an alliance with barabarians, in the battlefield Erica could not fight so she choose to hurt her father by killing herself in front of him, to no avail as King Eldrake felt not remorse at the sight of his daughter taking her own life before him.
The second Oddworld game has several kinds of Mudokons working as slaves for the evil meat-making corporation. Inbetween others there are hyperactive ones who you have to slap to snap them back to sanity, and depressed mopey ones who need to be cuddled to bring up their spirits. But slap a depressed one and watch as he goes over the edge, and repeatedly hits himself in the head until he dies.
Intentionally done to the local priest, Minase, in Suika. And he deserves it too. First, he strangled his insane wife to death, which... might be overlookable since she was nuts. But then he comes across his daughter Itsuki, kills her with a shovel and buries the two together. He puts his other daughter Sayo, unconscious and badly bleeding after Itsuki herself threw her down a flight of stairs, in the hospital and doesn't even recognize which of the twins she is. When Akira finds all this out, he confronts him and recommends suicide.
In the The Thing video game, if your teammates get scared enough, they will pull out a pistol and shoot themselves in the head.
In Resident Evil Outbreak, certain members of your team will commit suicide if they have a gun and have been cornered by zombies or have incurred too much damage. Also, in the first level, you can recruit a sick (infected) security guard named Bob; if you help him up to the roof, he says something akin to the hunger being too painful and that he can't go on, then blows his brains out.
This happens if you scare the teddy bears enough in Naughty Bear.
At the end of Toshiko's series of missions in Grand Theft Auto: Liberty City Stories, which she has Toni perform against her husband Kazuki in revenge for neglecting her, culminating in his death, she realizes that she has lost everything, and commits suicide by defenestration as Toni watches.
The ultimate fate of Priscilla and Raven's parents, Lord and Lady Cornwell. For worse, Raven believes they were murdered, thus fueling his desire for Revenge.
Also, it's hinted that Ninian and Nils seriously considered killing themselves at some point, driven into despair after being summoned, captured and hunted down by the Black Fang. Thankfully, they don't go through it.
In the English version of the same game, the ending for Karla and Barte mentions that Karla dies of an illness. Afterwards her husband Barte gives their child to a relative and kills himself.
Someone killing themselves is actually a plot point in Fire Emblem Awakening. The dead person is Chrom's sister Emmeryn, who throws herself off a cliff to avert a war between Plegia and Ylisse that would tear the world apart. This selfless Heroic Suicide raises the Ylissean cause and causes almost everyone to desert Gangrel, the King of Plegia. Subverted later: Emmeryn is found to have survived (though at the cost of suffering Trauma-Induced Amnesia) and can be recruited as a playable character.
In a more traditional manner, Henry commits suicide in his ending if he's unmarried. Then again, it's Henry we're talking about, so no one (even in-universe) is surprised.
In the Birthright route, after the player defeats Flora, Felicia's sister, she sets herself on fire due to her sadness and guilt of double-crossing the Avatar. Later on, after accidentally killing Elise, Xander falls into despair and commits Suicide by Avatar.
In the Conquest route, Takumi decides it's Better to Die than Be Killed and jumps off the Great Wall of Suzanoh. Later on, at the end of Chapter 25 of that route, Ryoma commits Seppuku to prevent the Avatar from killing him. Unlike Flora, this counts as a Heroic Suicide, as he wants to prevent Garon from executing the Avatar for not carrying out his order to execute Ryoma. The first example then posthumously bites the suicidal person in the ass when the Greater-Scope Villain fully possesses his corpse and uses it as the Final Boss.
In the Revelation route, Gunter attempts this after the Greater-Scope Villain possesses him and forces him to attack the party, but the Avatar saves him and convinces him to atone with his life instead of his death.
Late in Valkyria Chronicles II, when the Rebels actually succeed in completely taking over Gallia, the sheer hopelessness of the situation causes Lanseal's headmaster to have a mental breakdown that ultimately culminates in him shooting himself in the mouth.
Shadow Warrior has a humorous version: the standard mooks that shoot Uzis at the player character seem to have a high enough sense of honour that they'll take their failure to kill him in the only way a honourable warrior would: by eating their gun and shooting half their skull off.
Mistress Astria will be kill herself, only if you manage to kill her loyal guard first, and considering the game it's actually the easier path as it's only him, becoming an Anti-Climax Boss depending on how you take out the guard, you can wear enchantments and stand just out of his sight of you and make a cloud of poison to slowly kill him.
Also, Ostrova, son of the king, will be driven to this no matter what, if you don't kill him first anyway, and you have to face his vengeful/sorrowful spirit a second a later, people's bad side being able to materialize as black phantoms, actually just dark red with a black motif.
In Sword of the Stars, Liir Black Swimmers who have had to put enemy civilians to the torch usually pilot their spacecraft into nearby stars after hostilities conclude.
In Hatoful Boyfriend it is revealed that Nageki killed himself five years ago. The full version gives context, and it's rough.
It's all but stated that Rin Tezuka might end up doing this, since in her route she becomes more and more self-destructive in her despair to get enough inspiration to create art, which does not mix well with how she cannot exprress herself unless it's through art itself. Also, that same route says that the husband of her sponsor, Sae Saionji, was a talented artist who also committed suicide, for exactly the same reason.
Something that's kinda overlooked by fans during early playthroughs is that Shiina Mikado aka Misha also has suicidal tendencies. In Shizune's route, during a talk with Hisao, she tells him "Wouldn't it be better if I disappeared...?" In the beta to the game, Mishawould have committed suicide in Shizune's arc. Act 3 is full of her acting increasingly depressed and reveals her self-loathing, only to end with her getting hit by a car and dying soon afterwards. Act 4 is all about her best friend Shizuneshutting down in grief. The Bad End actually has her essentially kill herself. Shizune dies of dehydration after being hospitalized if you don't stay in the hospital. She removed her IV.
One of the threeBad Ends to Hanako's beta arc has her jumping in front of train (in front of Hisao too) after undergoing a Trauma Conga Line. This is the closest thing to a Good End her arc has. To unlock the true Good End you need to have played her arc then play Lilly's arc, until a point comes where you can choose to unlock the true Hanako end appears.
In the 2012 reboot of Syndicate, it's possible to hack other people's DART chips to force them to kill themselves.
Dead Rising 2 has Brandon Whittaker, who slits his throat with a shard of glass after getting bitten by a zombe he kept in a bathroom stall to "spread the goodwill",, Leon Bell, who lit himself on fire for quadruple points rather than get killed by Chuck, and Amber or Crystal Bailey depending on which one you killed.
Fairly late in The Way 2, the main character comes across a guy threatening to jump off a cliff. Given the proper dialogue choices, you can talk him down or convince him to jump, or, if you're feeling really cruel, push him off yourself.
Konrad in Spec Ops: The Line, and Walker in several of the game's endings. Adams is last seen making a likely-fatal Last Stand, and seems in no doubt that he deserves to die by that point.
If you decide that Carlos was the one who murdered Junpei he'll slit his own throat.
At one point Diana is forced to shoot Sigma with revolver half-filled with blanks, otherwise Phi will die. If Diana ends up killling Sigma she'll join him.
In one of the secret endings of Arfenhouse 3, Licorice Guy, the arch-nemesis of Candyland, throws himself over the waterfall, overcome both by the shame of having killed his mother there and by the realization that he's in an Arfenhouse game. Joseph, tired of being the Only Sane Man in the party, then decides to follow his example.
In Bioshock Infinite, human enemies hit with the Possession vigor will kill themselves when it expires. It's not quite clear whether the mind control is instructing them to do so or whether they just can't live with themselves after being forced to fight on the same side as the man they've been told is The Antichrist.
Happens in Bioshock 1 and Bioshock 2 also. Andrew Ryan mind controls the player into killing him but a quick look at audio diaries, corpse placement, and a few other things will show that quite a few people in Rapture elected that way out. One of the easiest examples to find is in the apartments. Some girls, their parents, and a jar of poison while the TV shows "please stand by".
In Remember Me, one of Nilin's memory remixes makes Forlan believe that he killed his wife, causing him to commit suicide.
In S.T.A.L.K.E.R.: Call of Pripyat, if you manage to solve the mystery behind the missing stalkers in the first map, you'll find that The Medic from the main wrecked ship was responsible for their deaths. He explains that he [[used to work in a surgeon's clinic and became terrified of seeing his patients undergo gruesome procedures. Over time, however, he developed a clinical condition that causes him to crave the taste of blood and made him lose his sanity. When he came to the Zone, he snapped from the inside and started to secretly murder stalkers when they least expected it and disguised them as bloodsucker attacks. After he tells his story, he guns himself on his chin. However, you can avert this by shooting him yourself, though you have a couple of seconds to do it before he offs himself.
In Persona 2: Innocent Sin, the heroes meet a ghost of a teacher who threw himself into the gears of the school's clock tower. Officially it was ruled a suicide, as he had just gone through a very acrimonious divorce and was showing signs of depression. His ghost says he was trying to prevent the end of the world, having interpreted an obscure prophecy as alluding to the clock signaling the beginning of the end, and he thought that if he killed himself in the tower the school would turn it off permanently. It was a little of both and then some, because he was haunted by the Big Bad, had his life ruined, and finally at the end was given a little "push." Also, if you end up making the wrong choice at a certain point, Anna Yoshizaka will commit suicide by jumping off a bridge.
A more sinister instance occurs in Persona 5. While Coach Kamoshida is already a serious asshole who exploits those around him and literally strikes down anyone who resists, he takes it even further by blackmailing Ann into paying a "visit" to him by putting her friend Shiho's spot on the volleyball team at risk. When Ann turns it down... well, it's implied that Shiho was assaulted by Kamoshida both physically and sexually, resulting in her taking a dive off the roof of Shujin Academy; Shiho survives, but she's out of commission for a good long time.
Persona 4: Dancing All Night's story mode begins with a girl hanging herself. Over the course of the plot, she's revealed to be Yuko Osada, an Idol Singer who could no longer handle the pressures of her job.
In RefleX, Raiwat commander-in-chief Tsukikagerou is so utterly ashamed of failing to capture the ZODIAC Ophiuchus and being forced to retreat that he kills himself.
Transistor has a few cases. Asher and Grant Kendrall kill themselves before you can fight them, after the former confesses to their crimes. And in the end, Red does this to herself to be in the Transistor with her boyfriend.
In This War of Mine, any survivors that delve too far into depression without any respite will eventually take their own lives.
Kate Marsh from Life is Strange will try and kill herself in Episode 2. How that turns out is determined by the player's choices.
Blank Dream opens with Mishiro attempting suicide, transporting her to the purgatory-like Mirror Realm. In order to get closer to granting her wish, she needs to find all of the mirrors holding her reflection, relive the memories inside, and find some way of killing herself within them.
In the currently under-development Yandere Simulator, Yandere-chan can lower the reputation of a rival within the school to dire levels with malicious gossip either at school or on the internet, which will lead to the girl suffering serious bullying. If you lower a girl's reputation to -100, Senpai will reject her Love Confession, which is enough for Yandere-chan to eliminate her as a rival for his affection. Lowering her reputation even further than that is a pure exercise in cruelty, and will eventually make things so bad for her that not only does the entire school hate her, but they want her to die, which ultimately results in the poor girl hanging herself.
Yandere-chan can also stage her murders as suicides by pushing girls off the roof and leaving their shoes and forged suicide notes above their bodies. The suicide notes all include a unique instigating cause for the suicide (e.g. sexual abuse, drug use), which Yandere-chan must obtain through eavesdropping earlier on.
Furthermore, Yandere-chan can kidnap students and quite literally torture them until they are broken mind slaves who will commit murder-suicide on Yandere-chan's command.
When you scare someone too much in Haunt The House, they will run to the nearest window and jump out.
Implied to be the fate of Dr. Alphys in certain Neutral endings. Broadly speaking, this usually occurs if you kill Undyne or Mettaton. Does not occur in the Golden Ending, but on the way there, you'll have a conversation with that character, after learning just why they might have "done something... cowardly" even if you did everything right.
Also a part of Flowey's backstory. After awaking as a flower in Asgore's garden, he eventually found that he couldn't feel any love or warmth from his parents. Not wanting to live in a world without love, he committed suicide. The only reason he is still alive is because, during his attempt, he realized he was afraid of actually dying, and that unwillingness to die caused him to wake back up in the garden as though nothing had ever happened. This is how he discovered his ability to save and load.
If you fight Asgore again (before befriending Alphys) and spare him again, he will kill himself in order for you to take his soul.
Asriel also wonders if this might be the reason the protagonist climbed Mt. Ebott at the start of the game.
Frisk... Why did you come here? Everyone knows the legend, right...? "Travellers who climb Mt. Ebott are said to disappear." ... Frisk. Why would you ever climb a mountain like that? Was it foolishness? Was it fate? Or was it... Because you...?
Lord Himuro kills himself after slaughtering everyone else in the mansion when the Calamity happened.
Yae Munakata hangs herself after her daughter went missing. Years later, her granddaughter Miyuki does the same when she's no longer able to cope with seeing spirits.
It's unclear if Sae Kurosawa hung herself or if the priests hung her, but Sae knew she was going to die and accepted it, certainly putting it close to suicide. To make matters worse, she's Yae's twin sister. They died the exact same way.
Itsuki Tachibana hangs himself after an attempt at helping Yae and Sae escape, not wanting to see them suffer the way he did after he killed his twin brother.
The fifth game, Maiden of Black Water has suicide as a prominent theme, seeing as how the cursed setting this time is a suicide hotspot, and how the ritual of the past involved shrine maidens witnessing suicides.
Most people who reach the final stage of Hinamizawa Syndrome die by clawing out their own throats - including Keiichi in Onikakushi-hen, Tomitake in every arc except Matsuribayashi-hen, and attempted by Satoshi in the backstory, though he was stopped. Also, Natsumi does this in Someutsushi-hen.
There are also several other deaths which appear to be Driven to Suicide, but turn out to be murder: Rika's mother in the backstory (seen to be murder in Matsuribayashi-hen) and Dr. Irie in Tatarigorshi-hen (seen to be murder in Minagoroshi-hen).
After the events of Tatarigoroshi-hen, Keiichi is driven to suicide in what is implied to be a different manner, since he was stopped and sent to a mental institution. Hey, if you'd just managed to curse death upon your entire village successfully after being shoved off a bridge by your adopted sister, you might go a little nuts too. However, Keiichi simply had a God complex. He thought he was a God, due to everyone he said he wished dead, died. Coincidentally.
Shion does the same thing as Keiichi in Tatarigoroshi-hen (and, implicitly, most other arcs with the exception of the "real" Tsumihoroboshi-hen, where everyone died in the school explosion, rather than the gas disaster), according to the victim roll. The only difference is that she isn't stopped. Not sure whether it's similar to what happened in Watanagashi-hen/Meakashi-hen, however. Although she wasn't implied to have had an episode of Hinamizawa Syndrome at the time, she could have easily been in the second wave of cases that Onisarashi-hen explores.
Rena, in every world, minus the "good" world. However, it's an attempted suicide prior to the series. She attempted to slit either her neck or wrists (depending on the medium) after a depression, but was caught before she bled out. She gets better, usually.
In Meakashi-henRika decides to stab herself repeatedly in the throat instead of allowing Shion to kill her.
Rika attempts suicide in Minagoroshi-hen as she doesn't want to see Satoko being abused by her uncle again. She doesn't go through with it because she knows that her suicide will only make Satoko's ordeal worse.
In Ending 6, Meirin is absolutely distraught after the party fails to save her Love Interest, and kills herself in the hotel room the next day.
In Ending 4, Saki and Meirinboth commit suicide. In his suicide note, Saki explains that he's terminally ill, and preferred to die by his own hand than let it catch up to him. Meirin's reasoning is less clear; presumably, she couldn't bear to live without him.
In Aubrey's Uncommon Time, we learn that their decision to participate in the hibernation experiment was effectively this; their depression was so extreme they felt that the only way they could have worth was to sacrifice themselves for Altair's success.
In The Classroom, this happens three times. First, on the fourth day, a student "can't take it any more" and throws themselves out of the window. Secondly, on the final day, the third student to arrive unexpectedly pulls a gun on the teacher and shoots him and the second student, before shooting themselves. Finally, also on the final day, the protagonist snaps after escaping the shooting and walks out onto the street. Though the first car misses them for what looks to be a Happily Failed Suicide, the second car doesn't.
In Vampire: The Masquerade – Bloodlines, you can help Imalia, a fallen idol turned Nosferatu, to exact revenge on her old rival, Tawni Sessions, who became a mainstream model after some time in the pornographic industry. After the player installs a bunch of webcams in Tawni's apartment, the press gets a hold of footage featuring Tawni, her boyfriend, and a llama having sexual intercourse. When the player visits Imalia again, she gleefully reports that Tawni committed suicide using pills and alcohol.
The Game Over sequence in the old management game Detroit, which happens if you end your year in the red too many times, shows your CEO drinking a last glass of water and climbing out of a skyscraper window.