Iron Lung Takes Its Mystery to Crush Depth—and Suffocates

Iron Lung

★ ★ ½

Iron Lung is a film made by YouTube star Markiplier (aka Mark Fischbach) based on an indie video game of the same name. The premise of both is that “The Quiet Rapture” has unleashed an apocalyptic event on Earth. Most stars and planets have vanished from the night sky, and the oceans are no longer water. They’re entirely made of blood.

Fishbach plays Simon, a convicted felon serving a sentence for blowing up a mining rig. In exchange for his freedom, his mission is to explore an uncharted section of the ocean to find resources. The entire film is Simon on a small submarine as he descends the ocean depths. Because the blood is dense, he can’t see anything out any windows. The sub is equipped with an X-ray machine that gives Simon an image of what surrounds him when he pushes a rectangular button.

Simon talks with Ava
© 2026 Markiplier Studios

Sometimes pushing this button is his only light source, as power drains and submarine catastrophes kill the electricity on board. For some reason, the X-ray still works, even when the sub is without power. He pushes the button. The X-ray scan appears for a few seconds on the internal monitor and fades out. It’s a neat gimmick that becomes overused by the time the film is done, at which point I wondered: why not just add more lights to the vessel? You know, since the ocean is made of blood and it’s hard to see out the windows.

The plot seems to follow that of the game—to take a sample of a creature in the ocean. The how, what and why aren’t really explained. Simon is just supposed to do as he’s told. I’m reminded of asking my parents why I couldn’t do something. Because they said so.

Caroline Kaplan as Ava
© 2026 Markiplier Studios

The film is shot well, proving Fishbach can both direct and act. Shooting the film on one location in a makeshift submarine pieced together from whatever scraps they have keeps the production budget down. The camera angles make good use of every square inch available.

But the first half of the film is boring, and by the time the action takes off, those who haven’t played the game are left confused about what Simon’s supposed to do. At some point, he should get an understanding of what he’s searching for—a realization that never quite arrives. If it did, I missed it. Mostly, it’s just Simon poking around the sub trying to figure stuff out.

At the story’s climax, Simon hears demon-like voices as something in the blood ocean is attacking his ship. The voices are indistinguishable, as the film is intent on keeping us in the dark. Fishbach leans too hard into the mystery and forgets we need a reason to get behind Simon and his mission. The reason never really comes.

Descending to the depths of the blood ocean
© 2026 Markiplier Studios

The story in the video game runs about an hour, even if completing it might take several. This film is double that, and it feels way too long. Shave 30 minutes off, give us a little more plot and the film could have been a solid indie sci-fi thriller.

There’s still enough to keep us mildly entertained. Certainly Fischbach has filmmaking talent, even if it’s unrefined. Fans of the video game will likely enjoy this more than the average audience member who knows nothing about the game going in. My takeaway from this film is to remember one thing: if my freedom were on the line, dependent upon my surviving crush-depth exploration in a sea of blood, get the contract signed. Have them sign it in blood. There’s plenty to go around.