I am putting this up here for peer review and contribution. I acknowledge that ideas are what i am best with so I don't mind if others expand upon them to make them better.

I keep coming back to why after so long the technology most 'medieval' cultures would have haven't developed in Duirt. Such as Arbalist's or canons or what not, one would assume that even alchemists would find an explosive method that would fire bullets, right? Or some way to use runes to create fire in enchanted barrels and launch musket balls. But what if the plane of fire was discordant with this particular material plane? So explosive magics or certain fire magics are difficult, also makes it so that elements like volcanoes and saltpeter are rarer.

Perhaps before the age of man, there was a great conflict between the elemental planes and the consequences of that war, due to the actions of the Fire planar inhabitants, is that their plane is ever outta complete alignment with the material plane.

Well, that thought just assumes that every culture and reality would would come to the same conclusion that launching a small chunk of metal out of a tube is a great weapon.

Simply put magic which already has the explosive power of saltpeter/sulfer (canons, guns etc). Why use a canon when you can get a wand of fireball? Or bring your buddy who can shoot lightning from his fingertips. There's been no need for the technology. And there's no "non-magic groups vs magic groups" where as the non-magical people needed to come up with an answer to counter the magic casters, each society has both magic and non magic working together within it.

This is also not an "official" DM answer but my own personal reflection as to why there aren't guns or canons in this setting.

Firearms were created shortly after fireworks. The first recorded firearms were used in China or japan, long before Europeans used them. Also, the other reason firearms are used, is because everyone can use them...as opposed to people who are specifically trained in "use magic device"

I understand the timeframe of when firearms were made, it's not relevant to the point I'm making. I'm just saying, why bother making firearms when there is an abundance of magic users on all sides of the playing field. I'd get it if lets say Eccles had NO magic and Vorus had tons, Eccles would've needed to create something to counter Voran spells. But that wasn't the case.

It kinda is though, because mages are not as common, nor as controllable, nor as craftable as a firearm. This is why it's important that there is an explanation. No a fireball is not a gun, it's more like a grenade, oh yes you can do that with alchemists fire which is napalm, however there aren't alot of alchemists, there are not alot of wizards and you can't have a platoon of mages on a battlefield and have them all drop fireballs because at best they can, each only drop like 3 a day. That's assuming you can coral such an independent and rare resource as Magic users. IT's why adventurers tend to be independent mercenaries rather then soldiers. So far as we know there is no Voran Mage army, otherwise there would be very little left of battlefields.

The other thing that firearms accomplish that has nothing to do with explosives, is it allows any poor fool to be drafted and used as a ranged combatant, not everyone has the skill to be an archer. Not just anyone can be a bowman. Crossbows, to a degree take up this potential position however they don't deal nearly enough damage.

As for why this is even remotely important, one should understand their setting right? I mean immersion comes from understanding.

I'd have to say as a Theory not an official DM answer, but maybe there is a group of people or even a Divine that is actively preventing the creation of this technology. Alchemist Larry is on the verge of discovering gunpowder [black powder]. Secret group one kills him in his sleep and destroys the lab so no one else can reproduce it.

But there was a Voran Mage army; that IS in the history of the setting. There was a war between Vorus and Eccles, that history became part of the reset. So as far as we know Vorus still has combat mages. And it's not rare enough that it's only adventurers practicing magic. There's two TOWERS of full of students in the setting AND an entire church full of divine magic users. There's plenty of other spells besides fireball such as lightning bolt, acid arrow, magic missile...I could go on and on, the point being, no farmer with a gun is going to be as effective. And I highly doubt that IF another war were to spout off there would not be Mage platoons. North and South Vorus are nations controlled by magic, so it's prolific and common enough.

Alright, nevermind then...

The following are my personal musings on this interesting question - they are not decisions about the setting, rulings about the game or even applicable as facts about the world. Just my personal thought experiment of sorts to see where it leads and hopefully help in the conversation.

The laws of physics in Novus Utum are not necessarily the same laws of physics that apply in the real world.

The most obvious case of that is the existence of magic, which by definition violates any number of physical laws. But that does not mean that physics in Novus Utum is identical to real world physics with magic added on top.

Obviously many of the same effects are present in Novus Utum: gravity, time, basic biology, etc are all compatible with our real world experience, but that need not extend to every detail of reality.

Maybe the chemical formulas required to create an explosion are different than in our world as well. Thus, if you add sulfur, saltpeter and charcoal, it might not go boom. Even if it did, it might not scale up or it might not have sufficient force to launch a projectile.

If the chemical processes are different, it might be much harder to stumble upon it during experimentation, or it might be much harder to harness the power in a useful way. Different, rarer components might be required, if it is possible at all. All of that would complicate any invention process involving it, beyond what Tronram already raised.

Now, that does raise the question of "Why". Why is the world so different in this specific aspect when everything else is so similar. Fair question!

To be honest, your explanation seems to be as good as any, maybe the elemental plane of fire is indeed out of alignment. It would certainly make sense and I don't see a fundamental problem with the idea.

Not confirming or denying your theory mind you, just saying it'd make sense.

Yes but alchemists...will always find the formula for fireworks, and then firearms are a natural continuation, regardless of need. People who want power are going to seek it anyway they can. So even if there isn't a need for them by the ruling royalty, it doesn't mean that Ambitious Major houses won't look to inevitably usurp the king or queens power by creating a new method of warfare. It's how coup's happen, how revolutions are fought etc. The other component of this theory, that I personally loath to mention, is that it could also explain the nigh non existence of extra-planar blooded people. No Oreads, Sylphs, Efrit, Undine, Teiflings, or Aasimars. Something the cataclysm can change if the chat eventually allows them.

Again I refer back to the effectiveness; it'd be more effective for a usurper to come up with a more powerful magic that cannot be countered rather than an explosive that can be blocked like an arrow or other spells. Not to say that mages ALWAYS counter arrows / spells cause they still die like regular folk but they CAN be countered. And Magic is a much easier resource to resupply, get a good nights rest and boom back to full. But explosives require much more manufacturing and is resource heavy, cut off your supply and you're SOL. I maintain my point that in a HEAVY magic world where magic is fairly equally accessible to all; there has been no NEED or even a WANT to develop firearms. And all things considered; the common folk haven't really had a reason to rise up. From what we know of the chat setting; the peoples of the three major nations aren't heavily taxed or terribly mistreated and the slaves in North/South Vorus have no means to revolt. And we don't even know if the majority of them ARE mistreated once they leave the market. Or if even all slave markets in North / South Vorus are the same as the Market of Tears.

Again this is all my personal musings and deductions from what is commonly known about the chat, not as a DM or any official statement

You also say regardless of need but need and want are two very powerful motives and as of right now Magic covers both of those motives. No fireworks can match or exceed illusions or other performance spells, no firearm can match the destructiveness of fireball, lightning bolt or accuracy of magic missile....were I a person in this world I'd laugh at anyone who came up with firearms or explosives cause the world is already 3 steps ahead of it with magic.

Now as to why magic hasn't been applied in a more industrious sense to increase profits / production I don't have a theory for that.

Well.... using Reality to filter the view of Fantasy kind of defeats the purpose of Fantasy right?

A quick aside on Slavery, The Market of Tears in Duirt is harsh on slaves to "break them" so the new owners can control them. Once they leave the Market the Vorans are generally not harsh or abusive with Slaves. Floom is famous for buying slaves enmass and then freeing them and giving them to work in Frostville.