A decade after the show’s fourth season finale, we examine TV puzzle-boxes, from ‘The Prisoner’ to ‘Westworld.’

Ten years ago this month, the survivors of Oceanic flight 815 finally got off that damned island. Or rather, on May 15th, 2008, Lost aired the first part of a three-hour season finale titled “There’s No Place Like Home.” By its end, the Oceanic Six–which was really five survivors, a baby, the pilot of a totally different plane, and some Scottish guy they’d found underground–had made it off the Island and some were already considering going back. It’s complicated, but then again, ABC’s behemoth puzzle of a show always was.

Though Lost is known for kicking off a slew of mythology-heavy ensemble sci-fi shows, it wasn’t the first cryptic, puzzle-box series to capture the world’s eye; nearly forty years before Lost, the single-season UK program The Prisoner confounded audiences with exhilarating mysteries that went largely unanswered. While The Prisoner was made even more puzzling by its up-for-debate episode order, Lost solidified its place in TV history by experimenting with chronology in a purposeful way that was, in turn, impressive and exhausting–and perhaps never more audacious than in “There’s No Place Like Home.”

“There’s No Place Like Home,” like any good finale, has great moments of payoff. Penny and Desmond reunite. Ben kills the mercenary who killed his daughter. Sun buys out her father’s company. Claire is Jack’s half-sister. Sawyer gets his hero moment. Plus, the Oceanic Six are welcomed home like heroes, while we finally figure out why so many others stayed on the Island. And though the most memorable image of the finale is a two-way tie between Locke in a casket and the Island disappearing, the episode’s greatest achievement is in the masterful way it writes its disparate timelines back together.

The flashforwards we’d seen all season converged with the present timeline on the island in ways that were surprising, heartbreaking, and beautiful. Thanks to nimble writing by Damon Lindelof and Carlton Cuse–who by this point were juggling around twenty major characters and doing most of them justice–long-held questions were answered while new ones were being planted, all without stepping on the important character moments. In retrospect, this feels like the last time that the showrunners knew exactly where they wanted the show to go, and pulled it off exactly the way they wanted to pull it off.

It’s tough to decide if a story is greater than the sum of its parts–or even if it’s equal to them–when those parts are out of order. A non-linear narrative featuring dual (or sometimes three or four) timelines can be subtle or show-offy, impactful or ineffective. Let’s take this puzzle thing literally: when done well, non-linear narratives can eventually come together like the final pieces of a puzzle, something that fits perfectly, allowing you step back and relish the overall impression. For instance, when the second half of “There’s No Place Like Home” begins directly after the third season finale ended–with Kate stopping her car to respond to Jack’s bonkers assertion that “We have to go back!”–that feels like a great piece of the puzzle that is Lost, one we’re elated to find because we’d searched for it for so long. When done poorly, though, non-chronological stories are like a thrift store puzzle with mismatched pieces, a mess of bits that leave you frustrated when it doesn’t add up to anything.

Lost should be remembered for its emotionally approach to sci-fi and its willingness to think big, but the impact of its bold narrative timeline (flashbacks for three seasons, flashforwards for one, then time travel, then something dubbed a “flash-sideways” that most laymen still can’t explain) can’t be denied. From Breaking Bad to The Affair to The Flash to the fourth season of Arrested Development–not to mention tons of swiftly-canceled shows like Flashforward–TV has been experimenting with linearity ever since Jack Shephard first grew his depressed post-Island beard.

In Alan Sepinwall’s book The Revolution Was Televised, he says, “Over the years, every single broadcast network…has tried to ape some part of Lost or other…None of them has come close to capturing what made Lost work–starting with characters who will be interesting to watch, whether the secrets are answered in a timely fashion or not.” Although Sepinwall wrote this years before Westworld premiered on HBO, I think it applies perfectly to the most ambitious non-linear show since Lost. Westworld’s first season contained two major timelines that were several decades apart, a twist that plenty of viewers guessed weeks before the series confirmed it. Lost also surprised viewers with timeline revelations, most notably in the third season finale, but also in the fourth season episode “Ji Yeon,” which mixed Jin’s flashback with Sun’s flashforward before cruelly yanking the rug out from under us to reveal that the two weren’t actually together for the birth of their child.

However, as Sepinwall points out, Lost built a foundation of likable, interesting, well-rounded characters before attempting to pull that stunt. Westworld has done no such thing. By valuing the “gotcha!” moment and its aesthetic obsession with the failures of memory over cohesive character development at every possible turn (like when a revelation in “The Riddle of the Sphinx” involved the relationship between a character we’d been consistently misled about and one we just met, essentially a big “who cares?” moment), Westworld risks losing the thread. If it does, it’ll be one of a long line of shows that have alienated viewers who seek the lofty, exciting sci-fi that’s a part of Lost’s legacy.

Despite the high rate of failure among shows that have gained inspiration from the metaphysical desert island epic, there are still a few that toy with linearity in a satisfying way. In Breaking Bad’s gutting second season finale, “ABQ,” when we realize the meaning of the melted teddy bear in a swimming pool, that’s one hell of a final puzzle piece. In a different vein, A Series of Unfortunate Events employs a bait-and-switch series of flashbacks in its first season which mirrors Lost’s “Ji Yeon” episode in its ability to inflate hope before devastating viewers. Finally, surreal, auteur-ish shows like Twin Peaks: The Return, Atlanta, and Mr. Robot use chronology playfully yet deliberately, blurring lines between “now” and “then” at will before returning to an ordered timeline, and often providing only the most impressionistic answers along the way. These shows look only briefly to the legacy of Lost before pushing beyond it, widening the scope of what TV is capable of by deconstructing the puzzle altogether.