The character is fully aware that they are in the game and break the illusion of reality of the game's setting by either indirectly or directly addressing the audience.

Alternatively, they may interact with their creator (the writer or director of the novel, etc.). This is more akin to breaking one of the walls of the set, but the existence of a director implies the existence of an audience, so it's still indirectly Breaking The Fourth Wall.

This trope is usually used for comedic purposes.

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