Unreliable narrator
Also said as Lying narrator
The one telling you the story is wrong, biased or lying, and you are meant to catch them at it.
In a game, the player has a second witness: the game they are playing. When the voice and the play disagree, the gap can be the most interesting thing in the story.
Say it
“Have the narrator say the leap was perfect while the player is climbing out of the ditch. Never correct him on screen, and let the player catch him.”
Where you’ve seen it
In Call of Juarez: Gunslinger, old Silas Greaves tells his exploits in a saloon as you play them. When he is challenged or changes his mind, the level changes around you to match the new version.
Not to be confused with ludonarrative dissonance
Dissonance is an accidental disagreement between rules and story. An unreliable narrator is a disagreement you planned, and the player is meant to notice it.