“Metagame is any strategy, method or action used in a game which transcend a prescribe ruleset”
From Metagaming, Wikipedia
For example, in “The Stanley Parable”, the narration guides the player to reach the goal, however, the player is not necessary to follow the instruction. This change affects the game to have several ending depend on each decision the player had made.
The game experience in each game-play is fully controlled by the player’s decision which leads the difference between each game-play.