Iron Lung review: Markiplier proves he belongs on the big screen

Markiplier is a YouTuber who independently funded, wrote, directed, produced, and acted in his very own debut feature film. And despite my reservations about this project, he hit a stunning home run.

It’s not unheard of for content creators to make their way to the big screen; oodles of influencers have starred in movies and even directed their own films, mostly to middling reviews. (TikTok star Addison Rae’s divisive performance in He’s All That comes to mind, as does YouTuber Chris Stuckmann’s “clunky” directorial debut in Shelby Oaks.)

When I sat down to watch the very first public screening of Iron Lung, I wasn’t sure what to expect. The movie is a totally independent venture, without any of the massive funding that major Hollywood productions receive. It’s a passion project in the truest sense of the word, into which Mark literally poured his blood, sweat, and tears. Given these details, I found myself heavily skeptical of whether or not he could pull off a true-blue feature at scale, especially given he was also its starring actor.

Iron Lung, the indie horror game on which the movie is based, is quite similar in this regard. David Syzmanski crafted the simple, retro-style horror game all on his own in 2022, which instantaneously cultivated a massive fanbase, including Markiplier. 

The two had a meeting of the minds about this. Mark, having created a few award-winning interactive series on YouTube in the past, even starring in sci-fi show The Edge of Sleep, had plenty of showbiz experience under his belt. Syzmanski had the vision. The issue was turning the dial from what fans expected of an influencer-funded project up to eleven… and boy, did Markiplier succeed.

Iron Lung brings its A-game in claustrophobic cosmic horror

Markiplier Studios

Iron Lung doesn’t do any hand-holding when it comes to worldbuilding. Much like the game’s player-controlled character, viewers are thrust headfirst into a dying world populated by scattered colonies of desperate humans searching for the answer to the ‘The Quiet Rapture,’ an apocalyptic event that resulted in the sudden disappearance of all habitable planets and stars.

What remained were moons covered in oceans of blood. Markiplier’s character, a convict named Simon, is tasked with exploring one such moon all on his lonesome in a slapdash submarine that certainly doesn’t feel safe enough to hold fast at great depths. If he gets enough data from his expedition, he’ll earn his freedom… or so he’s told.

This background information isn’t something that’s spoon-fed to you with explanatory dialogue or expository text. Instead, viewers are left to put the pieces together themselves through conversations between Simon and his handler, esoteric flashbacks, and Simon’s own revelations during the course of the film.

Simon’s venture through the foreboding blood ocean is somehow even more terrifying than the game on which it’s based. It’s instantly engrossing; Simon’s stress and fear is palpable, with viewers not knowing what’s coming within the bloody depths until it’s already there, revealed by the flash of a camera in the darkness.

It’s fascinating how such a small-scale project, contained to one tiny set with very few characters, can evoke strong dread and terror. But ultimately, that’s the strength of such a film; it allowed Mark to focus all his efforts on atmosphere and Simon’s gradual descent into madness as he’s met with one roadblock after another in his quest to escape the hellish waters surrounding him.

Those waters contain all manner of grainy, spine-tingling creepy-crawlies with teeth the size of trees and all-too-human-like eyes that bore into your brain. The scares in Iron Lung don’t seek you out — you find them gradually, stumbling upon them with each flash of the camera as the dread in your gut builds with every passing moment.

This style of horror is sorely missed in the current landscape of the genre, evocative of projects like Skinnamarink and Hereditary. Iron Lung forgoes jumpscares in favor of a slow, unhurried descent into hell that even I, someone who’s watched too many YouTubers play through Iron Lung, was terrified to see what would come up in the next photo.

Markiplier delivers a jaw-dropping performance in Iron Lung

Markiplier’s acting lends itself to this dread surprisingly seamlessly. As previously mentioned, I was worried that he would be an unavoidable distraction to the events at hand, dissolving the immersion completely. And at first, it was admittedly difficult to separate the YouTuber from the character he was playing. But that soon changed as events kicked off, with Mark effortlessly transforming into Simon the convict, a man at the end of his rope, terrified of what was to come, and grappling with the guilt of his past.

I left the theater wholly shocked at Mark’s acting skills. As an longtime Markiplier fan who’s been watching since the Happy Wheels days, I’m well aware of his voice-acting abilities and have watched through all his interactive series. He’s a solid actor, but I was skeptical of his abilities for such a demanding film — a horror movie, no less — playing one of the only characters on screen for two hours and seven minutes.

I needn’t have fretted. Mark’s acting shone bright throughout the length of the movie, punctuating his terrifying journey with moments of genuine anger, fear, desperation, frustration, and madness that left me slack-jawed. If you had no idea who Markiplier was before watching this movie, you’d think he was a traditionally trained actor, not a YouTuber who decided to make and star in his own horror flick.

Iron Lung score: 4/5

I won’t spoil any events of the movie that aren’t already out there in the video game. What I will say is that Iron Lung is a pleasant surprise and a genuinely scary horror film in all the best ways. It’s not cringey, and it doesn’t try too hard to scare you. It’s exactly what an Iron Lung adaptation should be — a bloody good time.

Iron Lung is in UK cinemas now, while the movie hits US screens tomorrow, January 30, 2026.