A "flashback" is when someone remembers or experiences a past event or memory in their mind, as if they are reliving it for a short time. Full definition
The game is told through flashbacks of his or her recently found war diary, depicting the events the new recruit took part in with familiar faces of the series. (darkstation.com)
The story unfolds in flashbacks as he tells a detective the story of what led him there. (markreviewsmovies.com)
It covers a period from 1970 to 2014 told through flashbacks which build up the suspense brilliantly. (writing.ie)