Humanity has conquered the stars. Countless planets across hundreds of solar systems are all populated by human life, or at least that was the case, until an event called The Quiet Rapture cut all contact between star systems. Every planet and star seems to have disappeared without warning, leaving only moons flooded with seas of blood, and the distant remnants of humanity attempting to salvage what’s left and stave off extinction. Certain survivors are sentenced to explore the horrific depths of these bloodied moons in miniscule submarines referred to as an Iron Lung.
Based on the independent horror game of the same name by David Szymanski, Iron Lung was written, edited, funded and directed by Mark Fischbach, who also stars in the film in his feature debut. Fischbach, better known by his pseudonym Markiplier, is a massively-popular and beloved Youtuber, at one point one of the most subscribed-to channels on the platform, with over 38 million subscribers as of 2026. Initially announced in 2023, the film originates from Fischbach’s love of the original game during a recorded playthrough, filming the same year but encountering delays with the SAG-Aftra strike and the prolonged process of finding a willing distributor. It eventually released almost fully independently, the result of a grassroots campaign to major movie chains in the United States; the dedication to get the film made is respectable, and the passion shows in the end result, for better or worse.
Iron Lung follows Simon, a convict, sentenced to serve out his penance as an expedition as opposed to facing the death penalty for a crime he supposedly didn’t commit. His horrific venture into the darkness below, in the aim of freedom and the survival of humanity, will lead him into horrors beyond imagination. Simon will have to adapt to the challenges the submarine throws at him, the unknowable and indescribable horrors outside of it, and his own mental collapse in his attempt to survive. Iron Lung is a single-location horror film, set entirely within this miniscule submarine, and that concept has inherent problems for many, especially given its 125 minute runtime.
This is the film’s biggest problem, without a doubt, as half-an-hour could easily be shaved off of this runtime with minimal changes required to the rest of the film. The middle section, from around twenty minutes in until about just over an hour and a half in, is plodding and tedious, slowing the pace to a crawl and killing any semblance of tension the film has. What works in a game does not work in a film, and because we aren’t experiencing the claustrophobic environment of the submarine ourselves as viewers, it just comes across as grating and boring. The third act is absolutely explosive, breaking the record for the amount of fake blood used in a film production, but it simply takes too long to get there.
The script, written by Fischbach, is surprisingly solid. Much of it takes dialogue, especially expository information, verbatim from the game, but the original elements of the story are relatively strong as well. There are a few moments throughout that come across as genuinely emotional, they’re just held back in part by external factors. The film’s attempts at humour are poor, but luckily these are few and far-between. The many voices and external characters that converse with Simon are by far the best written parts of the film, leaning into the cosmic horror of it all, with every character coming across as desperate and hostile to a certain extent in a way that really pushes the tension forward. However, when these external characters are absent, it’s incredibly noticeable, for the film really struggles to have any sense of momentum during moments without dialogue. As debut screenwriting attempts go, it’s good, with a quite naturalistic touch that really works in favour of the film.
Szymanski’s game takes around an hour to complete, effectively functioning as a good set-up to one big scare, so the film had its work cut out for it adaptationally. Most of the film’s second half is invented, with Szymanski’s creative approval, and you can tell because it feels very distinct and different to what came before, leaning into more of an Evil Dead-style gonzo horror approach. The game itself is pretty solid, albeit simple, and it’s adapted almost too faithfully here, contributing to the plodding middle section that really needs work. A part of me wonders if this concept would’ve worked better either as a short film, or a Jaws situation where the first half is all character and worldbuilding, with the second half set mainly in one location and full of tension. Regardless, fans of the game will be happy with how it’s adapted here, far more faithfully than some recent horror game adaptations such as the ghastly Return to Silent Hill.
On a technical level, the film shines and is very impressive. Carrying a miniscule budget of 3.5 million dollars, it looks great, with many of the sci-fi horror sequences genuinely really impressive in appearance and well-stylised. It’s well shot throughout too, with Fischbach’s biggest and best skill being direction in this film, and cinematographer Phillip Roy doing an amazing job at making the film have an interesting visual identity at every turn. They don’t play it safe in that regard, and I’m very glad they don’t, because it ends up being one of the best aspects of the film. The make-up, costuming and set design are all fantastic as well, and the monstrous creatures inhabiting the bloodied oceans of the moon are well-designed and terrifying in appearance, albeit shown a bit too often by the end. The most praise I can give the film is on this technical level, as it’s actually very well made, especially for a film independently financed by a Youtuber.
The success of Iron Lung as an emotional narrative is dependent on Fischbach’s leading performance and ultimately, he stumbles under the pressure. It is no easy task for an actor – any actor, even a more experienced one – to carry a single location, two-hour film, and I don’t envy Fischbach’s task here, but it doesn’t quite work. As opposed to the dialogue, which is quite naturalistic and human, Simon comes across as alternating between entirely flat as a character and a caricature of a human. It’s always too much or not enough, and I never bought into this character as a living, breathing person at any point in the film. It doesn’t help that we aren’t made to care about him at any point, so his reactions always seem overblown and dramatic, and the ambiguity about what he’s actually done to deserve this really builds an emotional wall between the viewer and the character. If he’s as bad as everyone says he is, why should I give a damn about him at all? It’s a stark contrast to other recent films with ‘flawed’ protagonists, such as Marty Supreme, which at least approaches the subject with more nuance and makes the character multi-faceted in order to allow human connection.
The rest of the performances in the film are all done through voice over, featuring talents such as Troy Baker, Elle LaMont, Rahul Kohli, and youtubers Rachel Hofstetter (also known as Valkyrae) and Sean McLoughlin (better known as Jacksepticeye). The best of these performances by far is Caroline Rose Kaplan, who voices the reluctant and emotionally brutal commander of the operation, the only character who gets any meaningful nuance throughout the story. She particularly shines in the third act, as her character takes an interesting shift that contrasts with Simon, but they don’t explore this as much as they should either, dropping it almost as soon as it gets introduced.
Thematically, Iron Lung explores the desire for survival, the nature of punishment, and whether the ends justify the means. Simon is trying to survive, but as is the rest of humanity, and those two desires contradict each other more often than not. Whilst we never truly find out what Simon is perceived guilty for, or whether he actually did it, the film debates whether any crime is worth such an extreme and grueling punishment, and at what point it becomes inhumane to even the worst criminals. The film also touches on existential themes such as the nature of remaining alive, and at what point you lose touch with your humanity by doing so, especially because of madness and physical devolution.
There’s a lot conceptually going on under the hood here, and it’s all quite interesting, but it’s handled poorly in the film, which spends far too long on benign moments of Simon problem solving in a submarine instead of exploring the actual meat on the bones here. It reminds me in a bad way of the Five Night’s At Freddy’s films, in that the concept is interesting but it feels underexplored, left as nuggets for young viewers to search for and come up with fan theories to put on Youtube. That’s just not my idea of good storytelling, unfortunately, and I’ll almost always be underwhelmed by a film that has cool ideas but is too lazy to truly explore them.
An important side note that I want to mention is the cinema experience itself, which drew the biggest crowd I’ve seen at a theatre for a horror film since the debut of Weapons last year. Whilst it’s a limited release, and general audience reception seems mixed, there’s clearly a lot of people who don’t usually go out to see a horror film coming to see this, and that in and of itself is exciting to me. I’m always going to root for the genre to go well, and if it takes more movies like this, then I’ll be able to get behind that, even if the end product is heavily flawed. It’s nice to see a lot of eyes on a horror film, and a horror game by extension, especially with the younger crowd who seem to be a relatively elusive cinema audience to capture.
Overall, Iron Lung is a truly commendable effort, ambitious for a directorial debut, and when it succeeds it works brilliantly. Unfortunately, it’s limited by a flawed lead performance, a truly excessive runtime, and a poor understanding of what to prioritise for a film as opposed to a game. Not often do I think something should explore themes more but be shorter, but that’s the case here, with the bloated length not being used in any meaningful way to explore the genuinely interesting concepts at play here. Technically, it’s impressive for sure, and the first ten minutes and last thirty are genuinely very good, but there’s too many flaws for it to be anything better than a mixed bag.
