Robert Zemeckis’ films have never felt especially personal. It’s not that he lacks a point of view, or investment in his work. It’s just that once he started augmenting the zippy comedy of his earliest films, like I Wanna Hold Your Hand and Used Cars, with the adventure, action, and effects work of Back to the Future or Who Framed Roger Rabbit, he has most often appeared interested in telling stories through technological challenges and innovations.

Even his more overtly emotional movies don’t play like acts of soul-baring. His 1994 Best Picture-winning Forrest Gump, for example, has heartstring-tugging moments. But it’s still a picaresque comedy that doubles as an extended demo reel on the art of seamlessly integrated visual effects, from digitally removed limbs to CG-sweetened sunsets and augmented crowd shots, all introduced long before this kind of technology became commonplace. Gump has been a major reference point in the marketing of Welcome to Marwen, Zemeckis’ latest project: the new film’s posters have star Steve Carell sitting on a bench, like Hanks on the Forrest Gump posters, and they name-check the earlier film. But Marwen is more self-revealing than Gump, or any previous Zemeckis project. It may also be the worst movie he’s ever made.

Previous competitors for this title include The Polar Express, Beowulf, and A Christmas Carol, his trilogy of motion-capture animated films from the era when Zemeckis decided 3-D animation and an unmoored virtual camera represented the future of filmmaking. Welcome to Marwen returns him to the uncanny valley to adapt the real-life story of Mark Hogancamp, subject of the 2010 documentary Marwencol. Hogancamp was the victim of a hate crime — he was viciously beaten outside of a bar after admitting his interest in cross-dressing. He ended up with brain damage, and lost much of his memory. Once he got out of the hospital, he channeled his trauma into art, creating World War II scenes in a scale Belgian village he called Marwencol, and populated with dolls resembling him and other figures in his life.

Zemeckis uses his technical prowess to take a movie audience into the doll-village, now named Marwen. He stages full sequences where Mark (Carell) imagines his soldier alter-ego, “Hogie,” interacting with a squad of female ass-kickers. The dolls are realistically animated, using the faces of real actors (including Merritt Weaver and Janelle Monáe) atop stiff, plasticine bodies. The movie opens with Mark already immersed in his doll world, and very much avoiding the outside one, where his lawyer insists he should appear at his attackers’ sentencing to make clear the extent of their crimes. When Nicol (Leslie Mann) moves in across the street and makes friendly overtures toward her new neighbor, Mark does something the movie implies he has often done in the past: He incorporates a Nicol-like doll into his Nazi-fighting scenarios, attempting to bridge his real and fantasy lives.

Welcome to Marwen could have taken a much worse approach to a lot of its plot points. Nicol has a ridiculously evil ex-boyfriend lurking around, but the movie isn’t about forcing a phony confrontation between him and Mark. And Mark is sweet, but the movie doesn’t completely romanticize him, or elide the ways his doll project awkwardly depicts his sexual interests. There’s a key emotional confrontation between Mark and Nicol that Zemeckis shoots in an unbroken, unflinching two-shot, upping the tension by simply refusing to cut around them as they face off.

Throughout the film, Zemeckis, as ever, uses his camera gracefully. Like his sometime collaborator Steven Spielberg, he knows how to efficiently capture visual information in fluid camera movements that keep the geography of his settings clear and clean, rather than cutting them into oblivion. But while Marwen is a smaller act of showmanship than his other recent live-action movies, it’s also more explicit about its use of effects.

Zemeckis engineers some impressive transitions between Mark’s real world and the doll world, but they’re not especially transporting. The visual effects are designed to provide a vivid, hyper-real version of Mark’s fantasy land, more intentionally strange than Zemeckis’ mo-cap experiments. But the doll sequences are so obviously designed to offer barely veiled commentary on Mark’s psyche that they don’t have much non-metaphorical breathing room. Both the dolls and the “real” characters tend to speak in exposition, and the movie takes a schematic approach that mutes its emotional tones, sometimes immediately after striking them.

Even with the elaborate make-believe, it’s hard to really get into Mark’s head when characters keep arriving to deliver just the right information to the audience, or prompting Mark to do the same. When the movie does occasionally withhold information, it’s hard to understand why. The revelation that Mark has lost most of his memory, for example, arrives surprisingly late, and it’s delivered in an offhand way that never comes back around to a payoff. Characters ask enough questions about Mark’s condition to fuel the exposition, then let it drop.

It could be that Mark’s psychology doesn’t much interest Zemeckis. By the time Welcome to Marwen is rushing through its big courtroom speech, the film has become a treatise on using visual effects as a storytelling tool — and possibly accidentally, an exposé on their limits. While the movie comes out in favor of Mark using his dolls for therapy while also facing his real-world problems, the clumsiness of this journey feels like Zemeckis trying to solve emotional problems with technological solutions.

Meticulously detailed CG dolls aren’t exactly cutting-edge tech, but they make an intriguing stand-in for the director’s preoccupations, with the “real” Mark as a director’s avatar. As if to underline the connection (and undermine the true-story component), Marwen is liberally sprinkled with references to other Zemeckis films. At one point, Mark builds a time machine that looks a lot like the flying DeLorean from Back to the Future Part II. Hogie twists his head around 180 degrees, like one of the women in Death Becomes Her. There’s even a moving truck prominently labeled Allied, possibly after the director’s previous World War II-related movie.

That movie, like his post-mocap films Flight and The Walk, integrated impressive visual effects into mostly-live-action stories with the weight of a “real” camera behind them, rather than the impressive but also impossible digital swoops of his animated work. None of them are quite as triumphant as his best earlier work (though the underrated Allied comes close), and the mocap movies are more interesting experiments than full-on crowd-pleasers. Zemeckis’ history of playing with technical tools and pushing the visual envelope makes Welcome to Marwen play, appropriately enough, like a hybrid. It’s both a calculated attempt to recapture some of the emotional magic of his successes, and a clinical analysis of how exactly humanistic but effects-driven filmmaking is supposed to work. These qualities make it fascinating, but ineffectual as a narrative — or even as a demo reel. Zemeckis seems to think he’s showing heart. Instead, he’s messily dissecting it.

Welcome to Marwen will be in wide theatrical release in America on December 21st, 2018.