Dragon Age II has an unreliable narrator in the form of Varric. On several occasions his interrogator points out his lies and he retells a section of the story. It doesn't help that in the game he tells Hawke that he is a compulsive liar. In fact, the game allows you to play through his exaggerations: for example, in the prologue, Hawke and his/her sibling are fighting a group of darkspawn, and are able to one-shot Hurlocks left and right, even curb-stomp an Ogre, before he's called out on it and the player replays that section at level one. The second time, the gang is raiding a mansion, and Varric bursts in through the front door and is able to mow down all the guards Scarface-style with his Automatic Crossbow.
"Bianca", his Automatic Crossbow initially appears to be an example of this, since it's ability to reload makes it unlike any other crossbow that exists within the setting. It's later clarified that it really does exist and was built by a friend of Varric's who was trying to corner the market on these kind of weapons, but "Bianca" was the only one that he could get to work.
World of Warcraft creators tend to cite unreliable historians — making it slightly easier to explain away various retcons — to the point "canon" is usually refered to as "lore".
Humorously demonstrated in the Badlands zone post-cataclysm where the player meets a trio of characters who each tell a story of their encounter with Deathwing as he carved the gigantic gouge across the landscape. Each tale is filled with ridiculous exaggerations and Blatant Lies, the other characters constantly calling out the tall tales and even invading upon the third one' story, interrupting his "epic confrontation" to keep on perpetuating their own bragging. And it's absolutely hilarious.
Interestingly, this only happens Prince of Persia: The Sands of Time if the Player Character dies. Since the Prince is the one telling his story, yet somehow fails to remember HE DIDN'T DIE until he actually says that he did.note Given the time-travel shenanigans and the fact that the Prince can in fact die quite a lot, but still rewind time, it's probable that this is just him getting confused with one of the many deaths that he actually undid.
As Yahtzeeput it: "And then I wall-jumped at the wrong time and fell down a chasm and died. Oh, sorry, I'm thinking of something else. What really happened was... I wall-jumped at the wrong time... and fell down... no, wait, hang on. In actuality I wall-jumped at the right time, then accidentally pressed circle instead of X and fell to my death - I'm not boring you, am I?"
Also used this way in Monkey Island 2: LeChuck's Revenge. Guybrush spends most of the game narrating his story to Elaine, and if you fail to escape from the torture chamber in time and are killed then she points out that this is impossible since you are talking to her.
In Photopia, the narrator of the fantasy segments turns out to be a babysitter who is telling the story to a little girl with her as the protagonist.
More than one puzzle in the aforementioned Hitchhiker game relies on the player working out that some of the room descriptions are lies. The game eventually gives in and admits the truth if you look at it hard enough.
Make It Good relies heavily on this. The player plays as a hardboiled detective, send to investigate a murder scene, but various little clues eventually reveal the PC was directly involved in the murder, and the goal changes from identifying the murderer to subtly meddling with the evidence and getting the blame off yourself.
The Interactive Fiction game Fail-safe's main gimmick is that you are giving the regular Interactive Fiction commands via a communication device to someone on a falling-apart spaceship. At the end of the game, he asks for the code to a laser in order to help prevent the ship from crashing. It turns out, however, that he was lying to you about him being a survivor of the attack and that he is really an enemy alien who boarded, and you handing him the laser codes has enabled him to attack and help his fleet. On the player's second playthrough (or the first if he or she catches on to the twist beforehand), you can instead give him the code to target the enemy ships and thus ruin his plan.
Cloud Strife from Final Fantasy VII seemed to have several retellings on a key event in the past before the game makes you play through his subconscious to figure out what the hell really happened. Cloud's narration of the events is completely accurate, in terms of events that took place. The only really unreliable aspect is that he told the story as though he was Zack.
Final Fantasy X has a particularly interesting example of this trope. Much of the game is told as a flashback by the main character. While not necessarily deceptive, he also does not reveal a number of key points. This parallels his process of discovery; the player isn't told anything explicitly until the point in the story where the narrator himself first learned them.
In the video game Pirates Of The Caribbean The Legend Of Jack Sparrow, most of the game is Jack recounting his adventures. Being Jack Sparrow, he exaggerates things quite a bit, which is sometimes lampshaded by having other characters point out factual inaccuracies in his stories. This allows the game to include giant spiders, frozen vikings, and a very different version of the events of the first movie.
Viewtiful Joe features a narrator attempting to make Joe's actions look heroic. The truth is Joe is having a blast being a superhero, completely forgets about his captured girlfriend, and more or less arrives where she is accidentally.
In Hitman: Blood Money, the game takes place in flashbacks being told in an interview by former FBI director "Jack" Alexander Leland Cayne, who's account contains multiple inconsitencies with what actually happens in the game. It turns out that Cayne founded "The Franchise" and was behind the "The Agencies" destruction and part of a plot to assassinate the President so that he couldn't forward his pro-cloning policy, allowing for Alpha Zerox continued monopoly on cloning. At the end of the game, Diana revives 47 in the funeral house and 47 kills everyone on the premises, including Cayne and the reporter performing the interview.
It's employed in other ways during the series as well. Several missions in the original Hitman: Codename 47 were remade for the third game, Hitman: Contracts, but in the latter instances the level architecture is different, some events play out differently from the originals, and all of them take place at night in dismal weather. The disparity is explained by the Framing Device of 47 having been shot and going through a near-death experience in which he recalls past missions; it's never made explicit whether the original version of the missions is unreliable, or the remade versions.
Every character in Twisted Metal: Black narrates their tale during the three cutscenes (opening, mid-game flashback, and ending). However, at least two of them find that the truth is far from what they thought... and neither get a happy ending.
The Silent Hill series has two unreliable narrators: James in the second and Alex in the fifth.
Possibly Shattered Memories: It is likely that the entire game involving Harry Mason takes place in Cheryl's head and it has even been suggested that the therapy sessions are also viewed in a biased manner, explaining Kauffman's poor attitude.
Captain Qwark in the Ratchet & Clank series built his career by telling bogus stories about his heroics that were either actually done by someone else or never actually happened. This is actually a major point in the Secret Agent Clank spinoff, where there are entire gameplay parts based on Qwark's ridiculous narrations. Amusingly, one of Qwark's apparent fabrications are "robotic pirate ghosts"... until Tools of Destruction revealed the existence of robot Space Pirates and Quest for Booty featured undead Robot Space Pirates, thus making his story seem much more plausible...
Haldos follows this trope closely in both Nexus War games, although despite plenty of Kick the Dog behavior on his part and the fact that he openly admits to learning what he knows directly from the Big Bad, there's nothing to actually disprove his claims.
Lampshaded in Penny Arcade Adventures where the narrator right at the start sets doubt in the player's mind as to his identity and motivation. "Please, do not dwell on my... mysterious identity. You're dwelling on it, aren't you?"
In Tales of Legendia, whenever the player sees Stella during a flashback from Senel's perspective, she seems to be a Purity Sue. However, Stella appears a lot less than...idealized whenever the flashbacks are from Shirley's perspective. justified as A) he was madly in love with Stella, and B) deeply guilt ridden over the role he played in her death.
In Knights of the Old Republic, given that she gives you a lot of exposition, from background of the Mandalorian Wars to the whys of the Jedi Civil War to the reason the Exile was... exiled by the Jedi Council, Kreia fits this description.
Making Kreia possibly unique as a party member in RPG history — she is always lying about something.
This trope is an excellent summary of Touhou. Each of the various routes in the games (depicting different characters or even the same character experiencing similar, slightly altered events) are all canon simultaneously. The universe compendiums are written by a reporter who hasn't even heard of journalistic integrity, a racist historian relying almost entirely on conjecture and second-hand reports with a massive dislike of the local youkai populace and who readily accepts bribes to smear and stroke egos, and a hyperactive thief obsessed with explosions. Even ZUN himself is prone to blatant contradictions, messing with the fans and outright lying. Inevitably, the Fanon is truly massive.
In a rare case of the games' Encyclopedia Exposita being this, the entries for the Pokédex are sometimes speculated by fans to have been written by the 11-year-old protagonists, and thus are likely to contain wild exaggerations about the Pokémon they describe. This would explain the games' use of Sci-Fi Writers Have No Sense of Scale, but then the Fridge Logic hits and you realize that this means that The Professor's life's work would be utterly ruined.
The Resident Evil Chronicles games depict the events of previous games through records and word-of-mouth. This results in some things that happened either glossed over or misinterpreted.
The near-entirety of Cry of Fear centers around and takes place within Simon's book as a personification of himself, making you wonder what inspired the events inside or otherwise aside from the obvious causes, like his insanity and being able to walk in it. Whatever caused them is (likely intentionally) left open to interpretation by those who play.
Rucks in Bastion doesn't lie, but his recounting of the game's backstory comes off as selective and self-justifying, including some whitewashing of aspects of Caelondia's history and culture.
There is a very, very subtle hint that this is how the story of Final Fantasy Tactics is unfolded. When Ramza meets Orlan Durai for the first time, the latter is shown capable of seriously overpowered magick ("Galaxy Stop!") while fighting the thieves that caught him spying in their guild; but Ramza and co must save him anyway as he's outnumbered. Such magicks are the domain of inhumanly powerful wizards, but Orlan is just a spy; in fact, later he can't use the same magick to stop Delita from (not-)executing him. Thus, a more likely explanation is that it's the narrator, Alazlam Durai, who exaggerates the power of his ancestor.
Jennifer from Rule of Rose is the King of this trope. Everything that happens in the game, when taken literally, is simply a metaphor for things that did happen. And when you think about the game's story like that, it makes even less sense.
In Spec Ops: The Line, some cutscenes Fade to White instead of Fading to Black. Those are the scenes in which the protagonist, Cpt. Martin Walker, is in some way deceiving himself, via hallucinations, delusions or other doubtful perception - and since he's the Player Character, that means he's lying to the player, too. This leads up to a pretty massive reveal at the end of the game.
Black. The intensity of the game is a reflection of Keller's recollection of combat under intense psychological pressure - both in the battlefield and in the interrogation room. So the winding levels, seeming endlessly respawning enemies that take a lot of damage to kill, ambushes, useless/missing squadmates that randomly drop in and out with no mention of where they went, labyrinthine level design, etc. are just how Keller recalls each mission, not how it actually was. This also explains the disjointed, almost non-existent story, as that doesn't matter to Keller as much as the accomplishing the mission does.
SpaceQuest runs on this trope quite nicely. He has little to no confidence in Roger Wilco during most of his adventures. Oh, and two games have actual voices for the characters, and who else would be picked to be the narrator than the famous Gary Owens?
Much of the in-game books and lore in The Elder Scrolls is written by people with a heavily biased agenda or simply wrong historical information. For almost any given concept or historical event, one can find several conflicting sources throughout the game. In particular, almost all of the in-game lore books in Morrowind are written by unreliable narrators (Almalexia and Vivec especially).
Errand combines this with Interface Screw to show that the main character phantasizes seeing e.g. a hungry dragon when it's really a complacent dog.
Despite BattleblockTheater's, ahem, eccentric narrator, it surprisingly tends to avert this. What he tells you seems to be what's legitimately going on in the game.