Friday Facts #386 - Vulcanus

Posted by Earendel on 2023-11-24

Hello there,
I know a lot of you have been eagerly awaiting some solid information on the new planets, if so this blog is for you. Get comfy because it's a long one.

As you already know, there are 4 new planets in the expansion. We will take an in-depth look at each planet's terrain, challenges, processes, technologies, and new gear, but not all at once. In some cases the planet content will be split into multiple parts. To kick things off I'll cover the terrain and natural aspects of the planet that is closest to being finished.

I'll need to be in games master mode for this:

Welcome to Vulcanus

Allow me to introduce this toasty volcanic wonderland, conveniently sandwiched between idyllic Nauvis and the sizzling sun. Vulcanus is closer to the sun than most would dare to venture but trust me, it's a splendid place to start your interplanetary travels.

Vulcanus planet icon

Our journey begins amidst the blazing volcanic mountains, imposing geological landforms that often feature a central lava pit. These fiery crucibles offer a great place to get rid of waste items; just throw them in and poof, they're gone in a glorious puff of smoke and flame. Outdated gadgets, cursed rings of power, maybe even unwanted company.

The highpoints of the mountains are the desolate ridges that surround the lava pits. This would be a good vantage point if it weren't for the thick yellow fog that burns your lungs and etches your eyes.

Further down the mountainside sulfuric acid geysers billow thick yellow smoke from fissures. The surrounding area is pitted by dried sulfur puddles while sulphur-stained rock covers a larger area.

Feel the rock crunch under your footsteps, this area has calcite deposits leaching out of the rock. It can be mined easily by your trusty mining drills but the many cliffs, valleys, and rocky protrusions render this terrain unsuitable for anything larger than a small mining outpost.

In the shadow of the mountains, the ashlands offer some semblance of tranquillity in this turbulent landscape. The thick plains of insulating ash are like cool comforting blankets that keep the worst of the heat at bay. Ashlands are the most habitable areas, but on this planet that's not saying much. It's mostly a desert but clusters of vegetation defy the harsh conditions to claim a precarious existence here.

The only resource here is coal; vegetation that was buried in ash long ago, compressed, heated, and exposed once again.

With flat terrain and sparse vegetation, if you're looking for a good location for a base you won't do much better than the ashlands.

Descending further, we reach the basalt basins where vast lava lakes and rivers have etched a labyrinthine network. There are many safe paths through but the routes tend to be circuitous. It's faster to go around, or over with elevated rails if you can. The lava, aside from being a formidable obstacle, is also a resource abundant with iron, copper, and stone.

Finally, the pursuit of tungsten beckons exploration deeper within the lava maze. That's why you're really here, right? With unyielding toughness, that little drill you brought won't do you much good. I'm sure nothing will mind if you mine a little...

...but who knows what might awaken in the depths of Vulcanus.

Designing the planet

When designing planets (or bodies) for a solar system, unless they are all moons then you'd expect different planets to be different temperatures with hotter planets closer to the sun and colder planets further away. Of all the planets you visit, there should be a hottest, and a coldest, and it didn't feel right for either of those to be Nauvis. (So as expected we have at least one planet hotter and at least one planet colder than Nauvis.)

Vulcanus is the hottest planet, named after Vulcan, the Roman god of fire, volcanoes, deserts, metalworking and the forge. The name is appropriate for both this planet's terrain and the planet-specific technology.

Being the hottest planet, I wanted Vulcanus to have lava. I got some pushback on this on the basis that “lava worlds are too cliche” in games. It's not untrue, planet uniqueness is certainly a high priority, but I had some counter arguments:

  • That would only be true if the planet was 1 dimensional and only about being lava-ry.
  • If we don't have parts of the landscape hotter than earth then as our hot planet, many people would find it underwhelming. The lava would be notable by its absence.

As long as the planet would still be interesting even if the lava were removed then it is still a strong design. Adding lava doesn't have to detract from the other features of the planet as long as it is done right.

So we have a volcanic planet, but it's more about the ashy plains, the mountains, and the sulfuric acid geysers than the lava rivers and volcano tops. Also it's worth noting that earlier in the planet's development there were some additional forms of vegetation, but those were later moved to a different planet so that we could amplify the specific desolate and scorched atmosphere that makes this planet unique and distinct from the others.

On this planet, I wanted the different areas to be useful for different things so that you treat them differently and adapt to the landscape. You can't just pave over everything (until ultra late game), so initially each area has a role.

  • The ashlands are a great place to build because they are flat and can easily be cleared of the sparse vegetation.
  • The mountains have 2 critical resources you need immediately, but they are difficult to build on until you get cliff explosives.
  • The lava rivers area starts as an obstacle but later transitions to be the most important area to mine.

On the map you can see the mountains as the large circular structures, lava basins and the areas with many lava rivers, and ashlands are the remaining flatter areas with green specks (trees).

A map of vulcanus

Over time, the lava has become more of a pivotal part of the gameplay because it provides a lot of new opportunities: It is a new obstacle that you can't landfill (for a long time), a new resource, and a new way to void items.

So including lava, here's a breakdown of the resources you have available:

  • Lava gives you Iron, Copper, and Stone. The excess can be thrown back in.
  • Coal gives you coal, but with liquefaction you can get the secondary oils too.
  • Sulfuric acid geysers give you Sulfuric acid directly.
  • Calcite is a new resource which is only useful when combined with other things, such as sulfuric acid.
  • Tungsten is an ore that requires some special smelting methods compared to iron and copper.

Forging the planet

The map generation (landscapes, biome distributions, etc) was the hardest part of this whole process. I'm sure that I spent a lot more time designing and building the landscape itself than any single thing that goes on it. The task is a unique blend of maths, code and artistry. I'll cover more on how this was designed and made in a future FFF, trying to explain it now will make this post far too technical.

One area I can explain quickly though is the starting area: Vulcanus has a very predictable starting area compared to Nauvis and this is required not just to give you access to convenient starting resources but primarily to show you what sort of terrains that these resources appear on. Knowing the terrain associations is important here because, for example, if you want to find more sulfuric acid then you should be exploring mountains to find it.

The starting area has 3 distorted circles representing a mountain, basalt basin, and an ashland plateau. These circles have guaranteed resource patches of sulfuric acid, calcite, coal, and tungsten. The whole arrangement can be rotated and flipped to not look too repetitive across different game seeds. All of this is done with basic maths and trigonometry (plus a bit of distortion that we will ignore for now). If you're learning trigonometry and wondering if it is ever useful, yes, yes it is, this is just one of many ways.

The circles of the Vulcanus starting area

For the tilesets within each landscape, the nature of the setting steered us in particular directions; rock, ash, lava, etc, but there was still a lot of creative freedom within that. With volcanic rock for example, there are a lot of different ways it can look ranging from sponge-like pumice to folded glassy rock that almost looks like melted black plastic. We used a lot of reference photos to start the tilesets and gradually shifted them to something more purposefully alien. Factorio is a stylised game, but I try to make sure that when we diverge from reality we do it intentionally and not out of ignorance.

The typical workflow is that I'd either make a sketch of a tileset or gather some reference images, Fearghall would make the textures in Substance Designer and Blender, then we'd go through many rounds of me painting over sections of the tileset and Fearghall making adjustments. When things were close to finished then I'd do a colour-correction pass so that all the tilesets integrate correctly into their respective biomes.


The lava requires some special attention. I've made glowing lava in the 1.1 version of the game engine a couple of times now but I had to choose between something that has motion but looks like orange water, or something that looks like lava but has no motion to it. For the 2.0 engine lava, Fearghall made a prototype lava shader outside of the game and got something looking good using a multitude of texture layers and distortion.

Doing it this way round was good because then when the shader was implemented in-game by him and Posila, it was already known how many layers we'd need, what gets distorted by what, and so on. A more typical approach might be that the shader was coded by a programmer first and then the artists would try to work within the constraints of the system, but I'm sure giving the artist some say in the initial constraints saved a lot of time. That's not to say that there weren't revisions, there were many, but we have a lot to do and saving time with a good workflow where we can certainly helps.

As many of you noticed from a previous FFF deconstruction planner icon we have some new cliffs. We tried using darker versions of Nauvis cliffs but that just wasn't good enough. Cliffs for this planet and others are made by Lucas. On this planet the particular challenge with cliffs is making them visible enough. They're dark objects on a dark background, and for the north direction especially, the first versions were very difficult to see. I found that if I added a large fake shadow below the north-facing cliff and a top edge highlight on all the cliffs, then it would get them into a state where they are readable and still integrate well with the terrain. The trade-off is a bit of unrealistic light & shadow but usability is far more important here.

Vulcanus cliffs

You can see a lot of small and medium craters on the terrain and they are just decorative meaning there's no collision or interaction. They're flat enough to build on without it looking weird. If we tried to make larger craters this way it wouldn't work because they'd either have to look too flat to look natural, or they'd look steep enough but placing a machine on the edge would look wrong.

The solution is to make the craters collidable but then there are 2 more problems, the collision boxes are always rectangles so hitting invisible corners is annoying, and there's a flat part in the middle that looks buildable but isn't. We also wanted some partial craters which would mean even more special collision rules. The solution we came up with is more like a ring of special cliffs where sections of the ring can randomly be removed. Unlike normal cliffs we don't have special start and end sections, Fearghall has made sure that all of the cliff sections can visually overlap to make a full circle but still look right if they are on the edge of a broken crater. If I find a full circle crater I like to put turrets in the middle, like a little fort.

Vulcanus crater cliffs

Sulfuric acid geysers are both a regional point of interest and a resource. I designed these areas to look almost like a subregion in their own right. These areas aren't huge because they are resource indicators and if the region is too big then it's harder to find the right spots to place your equipment. Finding the right spots is also made easier by these resource nodes having yellow smoke (yes, we can have animated resources now). Jerzy has made the acid puddles of this section in a couple of ways, earlier on we had puddles filled with liquid acid, but we moved to dried up puddles to keep the planet feeling drier (also building on shallow liquid acid puddles didn't look right).

These thermal vent chimneys are one of the areas we diverge more from a typical Earth volcano. They add a lot of verticality to the terrain when you are exploring and help it feel a bit more alien instead of just an extreme part of Earth. The young chimneys are small, the medium ones are tall, and the old ones have crumbled back to their bases. The landscape doesn't change on its own but these little touches help it feel like it is a changing world.

I wanted the ashlands to look like a spectral burnt forest with dark leafless shapes looming over you. The 'trees' if that is even the right word for them, are alive but we didn't want them to look leafy or anything like actual healthy trees. Presumably they get most of their energy by breaking down chemicals instead of photosynthesis, or perhaps they exploit the temperature gradient between the bottom and the top of the ash. From that point of view they are maybe more of an endolith fungus, but they have trunk-like shapes and have a tree-like role, so for now we call them trees.

A lot of work has been done so far but there are still a few remaining placeholders. The obvious ones for now are the tungsten and calcite resource graphics, those will be replaced soon. Hopefully the others don't stand out too much like the hand-painted decoratives in the ash-sand area because it may take longer to replace those.

Vulcanus decals


The path tears through ashy barrens and burning trees, winds around lava rivers and up jagged foothills, crunches through dusty calcite and splashes through sulfuric acid geysers to the top of a mountainous volcano. Just being here feels epic.

Vulcanus is the most developed new planet so far and getting to this state has been a big team effort involving most of the art team. When we return to Vulcanus you'll get to see some of the new processes of the planet and how the new resources are used. We'll also show off a couple of new structures, one that we've teased before. Can you guess which one it is and what it does?

As always, erupt your thoughts to the usual places.