A time loop or temporal loop in fiction is a plot device whereby characters re-experience a span of time which is repeated, sometimes more than once, with some hope of breaking out of the cycle of repetition. The term "time loop" is sometimes used to refer to a causal loop; however, causal loops are unchanging and self-originating, whereas time loops are constantly resetting: when a certain condition is met, such as a death of a character or a clock reaches a certain time, the loop starts again, with one or more characters retaining the memories from the previous loop.
An early example of a time loop is used in the short story "Doubled and Redoubled" by Malcolm Jameson that appeared in the February 1941 Unknown. The story tells of a person accidentally cursed to repeat a "perfect" day, including a lucky bet, a promotion, a heroically foiled bank robbery, and a successful wedding proposal. This story was a precedent to the films Mirror for a Hero (1988), 12:01 PM (1990), and Groundhog Day (1993). The time loop is also considered a familiar anime trope, since its use in the 1980s anime works Urusei Yatsura 2: Beautiful Dreamer (1984) and Kimagure Orange Road (1987).
Time loop as a puzzle
Stories with time loops commonly center on the character learning from each successive loop through time. Jeremy Douglass, Janet Murray, Noah Falstein and others compare time loops with video games and other interactive media, where a character in a loop learns about their environment more and more with each passing loop, and the loop ends with complete mastery of the character's environment. Shaila Garcia-Catalán et al. provide a similar analysis, saying that the usual way for the protagonist out of a time loop is acquiring knowledge, using retained memories to progress and eventually exit the loop. The time loop is then a problem-solving process, and the narrative becomes akin to an interactive puzzle.
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- García-Catalán, Shaila; Navarro-Remesal, Victor (2015). "Try Again: The Time Loop as a Problem-Solving Process in Save the Date and Source Code". In Matthew Jones; Joan Ormrod (eds.). Time Travel in Popular Media: Essays on Film, Television, Literature and Video Games. McFarland & Company, Inc., Publishers. pp. 206–209. ISBN 9781476620084. OCLC 908600039.