True to the video game, the camera never leaves the Iron Lung (a mini-sub with a dark past), and that choice may come as a shock to viewers unfamiliar with the source material. “Iron Lung” Courtesy Everett CollectionEarnest and likable but never quite enough to make Simon a proper person, Markiplier’s performance compounds that problem. Measured against the graveyard of other video game adaptations — especially recent studio misfires like Cineverse’s “Return to Silent Hill” — this deeply flawed attempt still stands as a testament to what happens when actual gamers make video game movies. As a case study, “Iron Lung” may matter more than it entertains. Grade: C+From Markiplier Studios, “Iron Lung” is in theaters January 30.