Dwarf Fortress forensic specialists blame mysterious case of spontaneous human combustion on a historical artifact that suddenly remembered it's four times hotter than the surface of the sun

The many wonders of Dwarf Fortress are products of its complexity. The intricate interplay of fantasy simulation systems generate uniquely rich moments: Fortress mayhem can provoke a rash of traumatic baby hauntings, goblin highwaymen can be grabbed and thrashed about by their individual teeth, and—as one Dwarf Fortress player recently discovered—sometimes your soldiers might just burst into flames in a way that requires a panel of experts to diagnose.

On the Dwarf Fortress subreddit, user waffle569 has been forced to seek input regarding "a catastrophic event slated to hit my save file in 10 days." The problem, they explained, is that every time they load their current save, a squad of their military's human mercenaries shortly returns from a mission abroad. And as soon as they reenter the map, they violently burst into flames. This, as you can imagine, isn't ideal.

Spontaneous Human Combustion from r/dwarffortress

Worse, the return of the doomed mercenary unit happens to coincide with the yearly arrival of an elven trade caravan, which gets incinerated by the mysterious detonation of the homecoming soldiers. While elven casualties are an unfortunate inconvenience, the real tragedy is the loss of their produce shipment, as waffle569 notes that "I need those crops for my beer."

While asking for an assessment, waffle569 provided some important context. One of the things that makes Dwarf Fortress so compelling is that player fortresses and roguelike adventurers become permanent parts of their world's history. When a player's fortress falls into ruin from attack or abandonment, those ruins persist. If you start another fortress elsewhere in that world, your dwarves might engrave statues or write tomes commemorating your fallen fort's deeds; you can even send military squads to reclaim valuables and artifacts from its ruins.

In waffle569's case, the squad of human enlistees had been dispatched to salvage what they could from the ruins of a fortress that had been destroyed by a dragon's fiery rampage 10 in-game years prior. Those soldiers' eventual spontaneous combustion, they hypothesize, might be related to the circumstances of that fort's destruction.

"My theory is that the items picked up by 'Josh' (or whatever the long folk call themselves) is still technically on fire from the first save," waffle569 said. "And once the item enters a live game, the fire resumes. Or maybe I'm cursed."

After discussing the matter, consensus in the replies is that waffle569 is on the right track—but the explanation is likely a bit more dramatic. The culprit behind the mercenary squad's unfortunate conflagration is probably Dwarf Fortress's handling of artifact items: named, storied masterworks of such high craftsmanship or legendary provenance that they become part of world history. Unlike normal items, artifacts are almost indestructible—but they can be on fire.

When the game stops simulating a region, the characteristics of the items present are saved—including their individual temperatures. But the effects of those characteristics aren't simulated again until the item in question reenters an active game region. An artifact that was on fire when a fortress was abandoned would then resume being on fire once it's reclaimed and brought back to an active fortress.

An artifact that was breathed on by a dragon is an exponentially worse problem to have, because dragonfire in Dwarf Fortress's simulation burns at approximately 40,000 °F—almost four times the temperature of the surface of the Sun. An artifact covered in dragonfire wouldn't just be hot enough to burst into flames; it'd reenter the simulation with a high enough temperature to flash-incinerate everything in the vicinity. Elven bystanders and their produce included.

"An artifact that was breathed on by the dragon would still be on fire with dragonfire, but the temperature calcs and implications wouldn't happen until it hit a play tile," said redditor K4G3N4R4, "causing your humans to go up in smoke with everything else."

Opinions differ as to how waffle569 might minimize the damage of the ensuing thermonuclear event. K4G3N4R4 said that waffle569 should simply wall off their beer fields and let the wildfire do what it will to everything else. Another user, 11912121121218211919, suggested carving out ramps where the squad returns that descend into water.

Depending on how efficiently waffle569's dwarves are completing their tasks, however, it might take too long to complete those preventative measures before the fortress suffers a thermodynamic disaster.

If nothing else, this serves as a valuable lesson: If you ever stumble across an artifact burning with dragonfire, leave it where you found it. Assuming you didn't catch on fire in the process, I guess.