Iron Lung is a 2022 one-man horror game from David Szymanski, the developer behind Dusk, released on Steam on March 9, 2022 at a launch price of $6, later raised to $7.99 in October 2023. It is a submarine horror game with no windows, no weapons and almost no light, and it frightens you by making you drive blind through an ocean of blood on the word of a map and a proximity beeper.
Story and setting
The setup is one of my favourite pieces of sci-fi horror worldbuilding in any small game. At some point in the future, an event called the Quiet Rapture wiped out every star and every known planet. Not destroyed them in a fireball, just removed them. Humanity survived on scattered space stations and a few moons, cut off from everything, with no idea what happened or why.
You play a convict. The people running what’s left of civilisation have found a moon, catalogued as AT-5, whose surface is covered by an ocean of blood. They want pictures of it. Nobody wants to go, so they strap a prisoner into a battered, barely seaworthy submarine, promise freedom on return, and lower the whole thing into the red.
The sub is the Iron Lung of the title. It is tiny, rusted and welded shut. There is no viewport. You never see the ocean with your own eyes, only through a crude exterior camera that spits out a grainy black-and-white image onto a monitor. Your handlers want photographs of specific coordinates. That’s the whole job. The game takes place entirely inside that cramped hull, across a single dive, and the entire story runs about an hour.
Everything about the world comes through text. A short briefing at the start lays out the Quiet Rapture and your situation. The rest you piece together from the few notes inside the sub and from what shows up in your photos. Szymanski is good at this kind of restraint. The Moon Sliver and Squirrel Stapler worked the same way, and Iron Lung is the purest version of it.
How it scares you
There are no enemies to fight. There is no inventory beyond a welding tool. Iron Lung scares you with denial of information, and it does it better than almost any horror game I’ve played.
Navigation is the core of it. You have a paper map of the trench on the wall, a readout of your X and Y position, and lever controls for forward, reverse and turning. You plot a course by reading numbers, nudging the throttle and watching the coordinates tick. When the proximity sensor starts beeping, something is close to the hull. A wall, a rock, or something else. You don’t know, because you can’t see.
The camera is the only window, and it is the cruellest mechanic in the game. Hit the button and the sub takes a still photo of whatever is in front of it. The picture takes a moment to develop. Most of the time it shows blood, rock and the occasional ruin. Sometimes it shows something that should not be there, and by the time the image appears you have already been sitting next to it in the dark. I found myself reluctant to press the button by the halfway point, which is exactly the point.
Resource pressure comes from the sub itself. Pipes burst as the dive goes on and you have to turn away from the controls to weld them. Every repair means a few seconds not watching the coordinates, not listening to the beeper. The hull groans. The pressure keeps climbing. The game never tells you how much the sub can take, so every clank reads as a countdown.
Sound does the heavy lifting. The engine hum, the sensor ping, the creak of the plating, and then long stretches where it is simply quiet. Iron Lung understands that an ocean with no sound in it is far worse than one full of roars. When something finally does make noise outside, it lands like a punch.
The pacing is a slow build with a small number of real spikes. I’d call the jump scares few, and the ones that are there are earned rather than cheap. There is no chase and no hiding. You cannot run from anything in a submarine that turns at walking pace, and the game knows you know that.
Gore is genuinely low. The ocean is blood, which is a constant unsettling idea, but nothing on screen is graphic. If you struggle with viscera this is one of the safer picks on our horror games list. If you struggle with claustrophobia or deep water, it is one of the least safe.
Lore and ending
Spoiler warning
The ending of Iron Lung, the final photograph and what the game implies about the Quiet Rapture get spoiled below.
The dive does not end well. As you work through the list of coordinates the photographs get stranger. Structures appear in the blood that look built rather than grown. The sensor starts picking up contacts that move. Near the final location, a picture comes back showing an enormous face, a vast open mouth and eye filling the frame, close enough that the sub is already inside its reach.
The creature attacks. The hull is breached, the screen goes dark and the convict dies in the Iron Lung. There is one ending and it is that one. You were never going to make it back.
What makes it stick with me is what the ending says about the setup. Your handlers did not expect you to survive either. The sub is a disposable probe with a disposable pilot, and the images were always the goal. Freedom was the bait that got a condemned prisoner into the seat.
The bigger question the game leaves open is whether the thing in the ocean is connected to the Quiet Rapture itself. Nothing confirms it. But the moon is covered in blood, the stars are gone, and something enormous is awake under the surface. Szymanski lets you draw the line between those facts yourself, and the game is scarier for never spelling it out.
Fans have spent years connecting Iron Lung to Szymanski’s other games, since he likes to seed shared imagery across Dusk, The Moon Sliver and his smaller releases. I treat those links as loose easter eggs rather than canon. Iron Lung works best read on its own terms: a short, closed story about a person sent into the dark to take pictures for people who already knew what was down there.
Then there is the film. Mark Fischbach, better known as Markiplier, played the game on YouTube in 2022 and his reaction helped turn a tiny indie release into an event. Fischbach went on to write, direct and star in a feature adaptation, with Szymanski assisting on the screenplay and making a cameo, and that iron lung movie reached cinemas on January 30, 2026 before heading to YouTube Movies. If you want the release details and box office numbers, we have a separate piece on the film. For the archive’s purposes, the movie is a separate work that expands the setting and the crew around the sub. The game is a solo dive with a single, grim ending.
Where to play
Iron Lung is a Steam release for Windows, priced at $7.99 as of October 2026, developed and published by David Szymanski himself. It is single-player only. There is no co-op, no multiplayer and no age gate on the store listing.
The requirements are tiny. It is a low-poly game built to look like something from the original PlayStation era, so it runs on almost any laptop from the last decade. That also makes it an easy Steam Deck pick. I played my second run on the Deck in a dark room with headphones and it was the better experience, because the small screen and the handheld closeness match the sub’s cramped cockpit.
As of October 2026 it is not part of Game Pass or PlayStation Plus, and Steam remains the place to buy it on PC. It goes on sale regularly, often for a couple of dollars, but even at full price it earns the hour you give it. If you keep a shortlist of pc horror games for a single evening, this belongs near the top.
If you liked this
Dusk for Szymanski’s other side, a fast retro shooter with the same eerie rural dread. The Moon Sliver for his earlier, text-driven cosmic horror on a dead island. Soma for a longer, story-heavy take on being trapped underwater with something you don’t understand.
FAQ
How long does Iron Lung take to beat?
About an hour for a first run, a little less once you know the coordinates and stop second-guessing the map. It is designed as a single sitting. Playing it in pieces drains the tension, so block out the hour and do it in one go.
Is Iron Lung based on a true story?
No. The Quiet Rapture, the blood ocean on AT-5 and the convict pilot are all fiction written by David Szymanski. The title borrows the name of the real medical device, the pressurised iron chamber used for polio patients, as a nod to a sealed metal box that keeps a person alive.
Can you see outside the submarine?
Not directly. The sub has no windows. The only view of the ocean is the exterior camera, which produces still black-and-white photographs on a monitor after a short delay. Navigation is done entirely by map, coordinates and the proximity sensor.
Does Iron Lung have multiple endings?
No. There is a single ending and the convict does not survive it. There are no branching choices, and the photographs you take do not change the outcome. The horror is in the inevitability.
Is the 2026 Iron Lung movie the same story as the game?
The film is Mark Fischbach’s adaptation, and it expands the world well beyond the single dive. It keeps the core idea of a prisoner sent into a blood ocean in a windowless sub, but it is its own telling rather than a scene-for-scene remake. Play the game first; it is an hour long and the ending hits harder when you have been at the controls yourself.