Immortality review – a spellbinding cinephile puzzle about a vanished actor

In the late 1960s, Marissa Marcel was an actor on the brink of Hollywood success. Beautiful, young and talented, she was selected from thousands in an open casting to star in a famous (and famously mean) director’s hypersexual arthouse-cinema adaptation of an 18th-century gothic horror novel. But the resultant movie was never released – and neither was her next picture. Marissa disappeared for years, resurfacing for a comeback role in the 1990s in another movie that never made it to theatres, before vanishing for good.

What happened to her, and what was going on behind the scenes of her unusual life? Presented with an archive of footage, you have the opportunity to comb through it all and try to find out. You’ll watch these three fictional movies out of order, piecing them gradually together, flitting between clips by highlighting a face or an object, which will then take you to another clip in which it appears. You can rewind and take screenshots to remind you of important moments, and I was writing down off-camera comments in a notebook.Immortality is an extraordinary thing, a documentation of a fictional film career replete with period detail. You will believe that you are rifling through real rushes from unreleased films, seeing real actors and directors and crews working the magic that creates cinema.

And hidden within this footage is a mystery so elegant and compelling that it can unfold naturally from any individual player’s investigations – no matter which clips you see first, or which character arouses your suspicions, or where your biases lie. The clips – hours’ worth of fascinatingly convincing takes and behind-the-scenes footage from movies that never were – are like petals that gradually fall to reveal an astonishing thing at the centre. With that match-cut magic, you can follow tempting rose-petal trails of motifs – an apple, a snake, a key – through time, through three different films, tracing the connections between them.

The sheer craft of it, the planning, is staggering. I can’t understand how it’s possible to engineer an emerging story like this, and yet this is the third time that developer Sam Barlow has pulled it off, after the excellent Her Story and Telling Lies. This game, comprising three entire interactive films, is the most ambitious of the three – and also the hardest to like, unafraid to risk boring you with hours of seemingly inconsequential video and reluctant to help you along the way to uncovering its secrets. Lovers of cinema history – like Barlow himself, and his co-creators – will find a panoply of references and details to marvel at in these fictional films, but if you’re just here for the mystery then it takes a long time to start to unfold.

Everyone involved in Immortality deserves praise for what has emerged here, a self-contained cinephile universe – not least the performers, who are all operating on at least two layers, actors playing actors playing roles. It’s impossible to delve into the deeper themes of the game without ruining its gracefully unfurling layers, but it has a lot to say about how films are made: the human cost behind them, image and identity, youth and sexuality, the drive to create something new and modern and the price of living for ever on screen.

I became lost in this archive, jumping from film to film, scene to scene, following threads, losing track of time. There are things I saw before the end credits rolled that others won’t have come across, and mysteries that remain because I never unearthed the relevant footage. But I didn’t want to go back to fill in the gaps, because my experience with this game felt so personal; I came away from it with a different story than the next person who’ll play. It is confounding and mysterious, but also spellbinding. I have never seen – or played – anything like it. It’s not a game that everyone will love, but I do think it’s one that everyone should play.

• Immortality is out now; £15.49 (or included with Xbox Game Pass)