Iron Lung movie review: Markiplier’s blood-ocean horror opens strong, divides critics

Iron Lung arrived in theaters at the end of January with an unusually large footprint for a self-financed genre release—and a reaction that’s split between admiration for its craft and frustration with its pacing. Markiplier, making his feature debut as writer-director-star, delivers an adaptation that leans hard into claustrophobia and cosmic dread, even as some viewers and critics argue the film stretches a razor-thin premise into a long haul.

This iron lung movie review roundup looks at what’s driving the buzz: a robust start at the box office, a carefully built “single-location” tension cooker, and a second-half swing that doesn’t land for everyone.

Iron Lung opens in theaters

The film’s opening weekend began with a strong first-day showing in North America, helped by wide theatrical availability and a fan-driven push for more screens. Early estimates put the Friday gross at roughly $8.9 million (ET), a notable figure for a hard-R sci-fi horror picture that trades recognizable IP for atmosphere and endurance.

Here are the key early numbers and benchmarks being discussed (figures are approximate):

Those figures don’t settle the long-term story, but they frame why the conversation shifted quickly from “Can this open?” to “How well will it hold?”

Markiplier’s bet on scale and control

A major part of the discussion around Markiplier is the way the release itself mirrors the film’s DIY intensity. Instead of a modest rollout, Iron Lung pushed into thousands of screens and treated the opening like an event—more akin to a mainstream genre launch than a niche midnight movie.

That approach changes the standard yardstick. With a wide debut, the film is judged in real time against broader audience expectations: story clarity, momentum, and whether the tension sustains beyond the initial premise. It also raises the stakes for word of mouth, because a film that’s deliberately oppressive and slow-burn will inevitably polarize casual viewers who expected a faster, jump-scare-forward ride.

What works: dread, design, and confinement

Even many negative takes concede that the film’s best stretches are its most minimal. The setup—an expedition that feels like a sentence—gives the movie a clean engine: limited space, limited visibility, and constant uncertainty about what’s outside the hull.

Common points of praise include:

• Production design and tactile realism: Controls, surfaces, grime, and cramped blocking sell the idea of life inside a metal coffin.

• Sound and pressure: The film weaponizes mechanical noise, silence, and sudden spikes to keep viewers braced.

• Commitment to mood: The strongest sequences avoid over-explaining and let dread accumulate from routine tasks, repetition, and small malfunctions.

When Iron Lung is purely experiential—lights, gauges, creaks, and the sense that something vast is nearby—it often feels closer to a chamber thriller than a typical adaptation.

What doesn’t: pacing, exposition, and tonal whiplash

The most consistent criticism is structural: the film can feel like two different movies stitched together. Many viewers like the early commitment to atmosphere, then lose patience when the narrative shifts toward heavier lore and explanation.

The main complaints tend to fall into three buckets:

1. Runtime drag: The tension built on repetition can flip into fatigue if the story doesn’t escalate cleanly.

2. Exposition overload: When the movie pauses to spell out its world and stakes, it risks deflating the fear that came from not knowing.

3. Noisy second half: Some reactions highlight an increase in audio intensity and plot density that makes the experience feel more exhausting than suspenseful.

None of that erases the ambition—it just explains why reactions have been sharply split, even among genre fans.

Forward look: holds, drops, and the “fan event” question

The next signal is whether the film holds in its second weekend. Slow-burn horror can be front-loaded: early audiences show up for the event, then the broader crowd decides whether it’s a repeat recommendation or a curiosity to skip.

Three observable factors to watch in the coming days (ET):

• Weekend-to-weekend drop: A modest fall would suggest the word-of-mouth is strong enough to offset the film’s polarizing style.

• Theater count stability: If the screen count stays high, it indicates steady demand; a quick reduction would suggest the initial surge was the peak.

• Audience response vs. critic response: The film’s trajectory will depend on whether general audiences embrace the mood-first approach as “immersive” or label it “overlong.”

Iron Lung may end up remembered less for unanimous acclaim than for proving something rarer: a creator-led, self-directed genre gamble can still open big—while sparking a real argument about what effective horror looks like on a mainstream-sized canvas.

Sources consulted: Variety; Deadline; IndieWire; IGN