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How to use TerraForge

This is a guide for your first visit. It explains what you can build, what every button does, and what happens to a planet once you save it. You do not need to know anything about space or 3D software to follow it. Read it end to end, or use the contents to jump to the part you need.

What this is

TerraForge is a planet builder. You choose the raw ingredients — the chemical elements a world is made of — then pick a star for it to orbit, set how far away it sits, and add moons. Press build, and you watch the planet form out of a cloud of gas and dust.

What you get at the end is not decided by you. It is decided by the physics: your ingredients and your orbit are run through a simulation, and the simulation tells you what they made. Put a lot of iron and rock close to a warm star and you may get something Earth-like. Pile on hydrogen and you get a gas giant. Freeze it out at the edge of the system and you get an ice world.

Every world you save gets its own page and its own link, which you can send to anyone.

A finished planet in the 3D view: a blue ocean world wrapped in white cloud swirls, lit from the left, with a faint ring circling it edge-on and a thin band of aurora glowing green and red at its northern pole. In the top-left corner a panel reads Habitability 58 out of 100, Marginal.
A finished world. The habitability score in the corner is the simulation’s verdict on what your ingredients made — 58 out of 100 here, which it rates Marginal.
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Building your first planet

Everything happens in the builder. If you would rather not start from nothing, open the Quick Start Presetsdropdown at the top — it reads “Select a preset...” — and choose something like Earth-like, Mars-like or Gas Giant. That fills in every setting for you, and you can change any of them afterwards.

Otherwise you work through three tabs.

Elements

There are 20 elements to choose from: hydrogen, helium, oxygen, carbon, silicon, iron, magnesium, sulfur, nitrogen, aluminium, calcium, argon, potassium, phosphorus, nickel, sodium, chlorine, titanium, chromium and uranium. You add them as “parts” using the plus and minus buttons — parts are just proportions, so four parts iron to one part oxygen means four times as much iron. Next to each element is an About button that explains what that element is and what it tends to do to a planet.

This mixture is the single biggest decision you make. It is what turns your world into rock, ice, water or gas.

The builder's configuration panel on the Elements tab. At the top, a Quick Start Presets dropdown reading 'Select a preset...', then three tabs: Elements, Environment, Moons. Below, a grid of colour-outlined element cards — Hydrogen, Helium, Oxygen, Carbon, Silicon, Iron, Magnesium, Sulfur, Nitrogen and more — each showing its symbol, a small question-mark About button, a count reading '0 parts', and a round minus and plus button.
The Elements tab. Each card is one element: plus and minus set how many parts of it go in, and the question mark opens an explanation of what it does to a planet.

Environment

  • Distance from Star, measured in AU. One AU is the distance from the Earth to the Sun. Closer means hotter.
  • Star Type. Ten to pick from: the hot, short-lived O, B, A and F stars; G, which is Sun-like; the cooler K; M, a red dwarf; and three stellar remnants — a black hole, a neutron star and a supernova remnant.
  • Initial Mass, in Earth masses, from 0.1 up to about 9,534 — that is 30 times the mass of Jupiter. There is a limit to how big a planet can be: push a hydrogen world past roughly 13 Jupiter masses and it stops being a planet at all. It ignites and becomes a brown dwarf.
  • Rotation Speed, the length of one day, anywhere from 1 hour to 2,000 hours.
The builder's configuration panel on the Environment tab, headed Environmental Parameters. A Distance from Star slider reads 1.00 AU. Below it a Star Type list of ten radio buttons — O Blue Supergiant, B Blue Giant, A Blue-White, F White, G Yellow (Sun-like) which is selected, K Orange, M Red Dwarf, BH Black Hole, NS Neutron Star, SNR Supernova Remnant. Then an Initial Mass slider at 1.0x Earth mass and a Rotation Speed slider at 24 hours per day.
The Environment tab. Two sliders, a star to pick, and a rotation speed — between them they decide how hot your world runs and how long its day is.

Moons

You can add up to 24. Each moon has a mass and an orbital distance measured in planet radii — so a distance of 5 means five times the planet's own radius out from the centre. The distance matters: bring a moon in too close and the planet's gravity tears it apart into a ring, and put it too far out and it escapes altogether.

The builder's configuration panel on the Moons tab. A short note reads: 'Moons shape the world over the aeons: braking its spin, steadying its seasons, kneading its interior. Too close and they shatter into rings or fall from the sky.' Beneath it is a single wide Add Moon button, and the rest of the panel is empty because no moons have been added yet.
The Moons tab before you add anything. Each press of Add Moon gives you a row with its own mass and distance.

Building it

Press Build Planet, or Ctrl+B. Formation takes about six seconds. You see the gas cloud collapse, material clump together, and a flash as the world is born, while a timeline counts forward from five billion years ago to Present Day. Ctrl+R starts over from a blank slate.

Once it has formed, the panel on the right tells you what you made: Physical Properties, Orbital Environment, Atmosphere, Elemental Composition, Surface Characteristics and Habitability. The build button becomes Edit Planet, so you can go back, change one number, and build again to see what it does.

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The buttons on the scene

A small row of icons sits on the 3D view. Hovering over any of them shows its name. Some only appear when they apply to your planet.

View planet
Shows the world itself, with its moons and any rings.
View star system
Looks down on the orbits from above, so you can see where your planet sits relative to the star's habitable zone — the band where liquid water can exist.
View surface
Puts you on the ground. It only appears once the planet has been built.
Show / Hide magnetic field
Draws the field lines around the planet. It only appears on planets that have a magnetic field. When the field is hidden, the magnet is dimmed and struck through.
Snapshot
Downloads a poster image of the scene with the planet's name, type, star and habitability printed on it.
Expand to full-screen view
Fills the screen with the scene, and puts it back again.
The star-system view: a black hole at the centre, seen from above as a bright ring of light around a dark core with a glowing orange accretion disc streaming out on either side. A wide green-shaded band marked by dashed lines circles it — the habitable zone — and a single small planet sits on its orbit within that band. A panel in the corner reads BH-type (Black Hole), Habitable zone.
What the orrery button shows: your planet’s orbit set against the green habitable-zone band, with the star named in the corner and a verdict on whether your orbit falls inside it. This world orbits a black hole — and still lands in the habitable zone.
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Standing on your planet

View surface drops you onto the ground. What you find there is read from the same numbers that shaped the globe, so it is your planet, not a stock backdrop.

Depending on what you built, you get bare rock, sand dunes, ice, lava, salt flats, or the cracked plates of a Venus-like world. On a world where the simulation detects life, there is grass and there are trees. On a water world you look out over open ocean. On a gas giant there is no ground at all — there is nothing solid to stand on, so you float among the cloud tops.

The colour of the sky comes from the star you chose. There is weather, there is wind, and there are mountains. And if one of your moons strayed close enough to be torn apart, you will see its debris arcing overhead as a ring. The surface view has its own snapshot button, so you can take a picture from down there too.

A first-person view standing on a planet's surface: tall dark-trunked trees with dense green canopies on a low rise, mossy green boulders in the foreground, blades of grass close to the camera, a stream running between the rocks, faint blue mountains on the horizon and a small white sun in a pale, hazy sky.
The surface of a world the simulation decided was habitable: grass, trees, running water and a pale sky lit by its own star.
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Saving, sharing, and why an account helps

You can build, save and share a planet without signing in. Name it, save it, and you get a link straight away that anyone can open.

There is one thing worth knowing before you do. A planet saved without an account is always public, and it belongs to nobody — not even you. That means it can never be edited, renamed, deleted or made private later. If you think you might want to change it, make an account first.

An account is free, and it adds:

My Planets
Your own library of everything you have saved.
Editing
Change a world after you have saved it, including its name.
Private planets
Keep a world off Explore and share it only with the people you send the link to.
Star systems
Group your planets around a shared star.
Likes
Give a heart to other people's worlds.

Signing in is an email address and a one-time 6-digit code that is sent to it. There is no password to invent and none is ever stored. You need to be 13 or older to make an account. If you are under 13 you can still build planets, save them and share them — you just do it without an account.

Your saved worlds live at My Planets.

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Star systems

A star system is a named group of your own planets that all orbit the same kind of star. You make one from My systems → New star system, or straight after saving a planet, using “Add to a star system”. You can have up to 10 systems, with up to 20 planets in each.

Two rules govern what fits. First, every planet you add must have been built for that system's star type — a world designed around a red dwarf cannot be dropped into a Sun-like system. Second, the spacing has to work. Real orbital physics checks each new planet against the ones already there. Orbits that would actually cross are refused outright. Orbits that merely sit close enough to go unstable over millions of years give you a warning, and then let you place the planet anyway if that is what you want.

The system's page shows the whole thing as an orrery — a top-down view of the orbits — and tells you whether the arrangement is stable for the long haul. Other people's public systems are at Systems.

The page for a star system called Gargantua Prime System: a black hole at the centre, drawn as a bright ring of light around a dark core, with nine planets on their own orbit tracks around it — labelled Melted World, Black Hole Earth, BH Venus, Gargantua Eden IV, Gargantua B, Pegesis IV, Gargantua Gas Giant and Gargantua Ice — and a green-shaded band, the habitable zone, crossing the middle orbits. Below, the system is titled Gargantua Prime System, described as a black hole system by Stargazer, and marked with a green badge reading Stable for the long haul.
A finished star system — nine worlds sharing one black hole. Each planet is drawn on its own orbit, the habitable zone is shaded green so you can see which worlds fall inside it, and the badge tells you whether the spacing holds up over millions of years.
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Finding your way around

  • Explore — every public world on the site. Filter by planet type, by star, or by a minimum habitability, and sort by newest, oldest, top habitability or most liked.
  • Planet types — what each kind of planet actually is, with a page for each one. A good place to look if a term in the builder is unfamiliar.
  • Systems — public star systems other people have assembled.
  • News — real exoplanet headlines, each linking out to the original publication.
  • The homepage — shows the Planet of the Week, plus recent worlds from the community.
  • The heart on a planet is a like. You need an account to use it.
The filter row on the Explore page: four dropdown controls side by side, labelled Type set to All, Star set to All, Min Habitability set to 0, and Sort set to Newest first.
The filter row on Explore. Narrow the list by planet type, by star, or by a minimum habitability score, then choose how it is sorted.
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Keyboard shortcuts

Two, both in the builder. Ctrl+B builds the planet. Ctrl+R starts over.

Surface views from three worlds: rocky ground under a ringed sky, a cloud deck, and a lit desert

New: Stand on Your World 🏔️

Every planet you build can now be seen from the ground. The terrain, the color of the sky, the weather and what hangs overhead are all read from the same numbers that shape the globe — so a thin-aired world gives you sunlit rock under a near-black sky crowded with stars, a runaway greenhouse seals you under an unbroken sulfur lid, and a gas giant leaves you in the cloud tops with nothing solid beneath you at all. If one of your moons wandered inside the Roche limit, what is left of it arcs overhead as rings.

Sign in or create your account

Enter your email and we'll send a 6-digit code — no password needed.
We only keep your email and the username you choose. We never share or sell your email, and we don't send marketing — we use it only to email you a sign-in code. Learn more.

Send feedback

We're still building out the best experience we can — and we'd love your input. Tell us about features you enjoy, ideas you'd like to see, or pain points where something feels off, and we'll know where to look next.

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