FREE to play

A whole planet.
Down to its burning heart.

A whole planet is yours: dig three thousand metres through rock, magma and crystal, down to its burning heart. Sail seas full of monsters, dive in a submarine, fly an airship, build anything you can imagine, then launch a rocket and land on other worlds. Free, in your browser.

No download. Click and play. Browser Android Up to 32 players No pay to win

Alpha now open: play free in your browser · join our Discord

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Two minutes in Mantlenaut.

Everything in it was recorded in the game itself: the world, the ships, the monsters and the stars. No mock-ups.

Freeto play, and no pay to win

3,000 mstraight down to the core

29legends to fight, and more coming

5,000+ships, cars and things in the Store

32players in one world

The planet

Every block is real. All the way down.

Mantlenaut's world isn't a surface with a floor. Under the forests, deserts and seas lie the crust, the mantle, the outer and inner core, and at the very bottom the Heart Chamber, where crystal pillars hum with a pattern no one has seen from the surface.

The deeper you go the hotter and heavier it gets, so you forge suits from what each layer gives you: copper to cool you, iron and steel to hold the pressure, tungsten and alloys of your own making for the last kilometre.

Explore the planet →

Surfaceforests, deserts, peaks, reefs0 m

Crustcaves, ores, glowcaps, lost ruinsto −300 m

Upper Mantlelava lakes, molten metal seasto −1,200 m

Lower Mantlewhite heat, crushing pressureto −2,200 m

Outer Corewhere Coreforged alloys are bornto −2,800 m

Inner CoreStellarite, and the hottest rock there isto −3,000 m

The Heart Chamberthe planet's secret−3,000 m

Sunlight through a shallow reef — Coralreach, where the light gets in

The Heart Chamber at the planet's core — The Heart Chamber, 3,000 m down

Sail · dive · fly

Build a ship. Then go anywhere.

Sea ships that really float: rafts, sloops, galleons, steamers, battleships. Sails, paddles, engines and rudders, and cannons that fire broadside.
Submarines with ballast tanks you fill and blow, down to where the pressure crushes a weak hull.
Airships held up by their gas bags, and pirates who fly them too.
The Shipwright draws a whole hull to your measure: length, beam, decks, engines, guns and bunks.
Walk around on board while it sails, with friends at the guns and the helm.

Ships in the Store →

A galleon under full sail on the open sea — Under full sail, in the game

Legends

Some things down there are bigger than you.

Boss · the deep sea

The Kraken

It sleeps at the bottom of the Hadal Rift, two hundred metres under the waves. Wake it and it fights in three phases: grabbing, sweeping, inking the water black and pulling you into a whirlpool. It hunts ships too, and snaps a held one in half. Its eyes are the weak spot. And it was never the one in charge.

Boss · hot sands and ash

The Mantle Wurm

Forty metres of basalt rings and magma seams that swims through the ground. You feel it before you see it: the rumble grows, then it breaks the surface in an arc, rears up, opens its four-petal maw and strikes. Only what's out of the ground can be hurt.

Thirty-one legends. Each fought its own way.

A walking whale skeleton whose worms rebuild it, an anglerfish that finds you by your light, a jellyfish that can't die, a crystal eel that swims through rock, a house on the sea floor that eats whoever walks in. Meet the monsters of Mantlenaut.

The Salt Pan King

Marrowking

The Unending

Goldgut

The Lanternfall

The Marching Keep

Meet the monsters →

Humanity's Reach

A carrier the size of a town, hanging in the sky.

Take the grav lift up into her hangar, where forty-six Viper fighters wait on lit taxi lanes. Climb into one, launch through the shield, fight with railgun and rockets, then fly back in to land. On her command deck, her crew work their stations. She's only the flagship.

A Wayfarer city with its banner over the rooftops — **Cities that grow**Villages grow into cities with their own names and banners. They trade, send convoys and gifts, and go to war.

A Wayfarer village — **People with lives**Wayfarers keep their hours, trade at their stalls, give you work and remember how you treated them.

Animals in a meadow by a lake — **Wildlife to tame**Win animals over with food, name them, breed them. A tamed Gloamstalker guards you.

An oil rig standing in the sea — **A planet with regions**A cold north, a hot south, oil in the east. Drill through the sea floor, refine rocket fuel, power your base.

Build

If you can imagine it, you can build it.

33 pieces from cubes, slabs, stairs and wedges to doors, lamps, pipes and cables, in any of nearly three hundred materials.
Forge your own alloys and compounds: new materials the game has never seen, with properties worked out from what went in.
Power and machines: generators, solar, wind and reactors; drills, smelters, pumps and conveyors, wired with real cable.
Blueprints and symmetry to copy, mirror and paste whole buildings.
Forge your weapons: blades, spears, and a full-auto assault rifle with a barrel of whatever metal you've found.
Eight ages to climb, from the Kindling Age to the Nova Age.

Everything you can build →

The build menu: every shape and machine — Every shape and machine, in whatever the planet gives you

Starforge

Make your own 3D models, right in the game.

Shapes, kits, letters and over 640 looks, and every part the game itself is made of, creatures and bosses included. Try it in your world with one click, then put it in the Store.

Meet Starforge →

A starship carrier, a galleon, an airship, a submarine and a monster truck from the Mantlenaut Store

The Store

Over 5,000 things for your worlds.

Galleons, battleships, submarines, airships, starships, cars, and thousands of things for your home. Free during the alpha.

Browse the Store →

Up to 32 explorers, one world

Open your world with a join code and friends are in it in seconds, from their browser or their phone. Dig a mine together, build a town, take on the Kraken as a crew.

Playing together →

Free, and no pay to win. Ever.

The whole game is free to play. Everything that matters is found, forged or earned in the world: nobody buys a better pickaxe, a stronger suit or a shortcut to the core.

Click and play

No download needed: it runs in the page on a PC, a Mac, a Chromebook or a phone. On Windows there is also the desktop app: the game on its own, on your best graphics card.

Beyond

Climb high enough and the world curves into a planet.

Then leave it. Build a rocket, fill its tanks and climb to orbit: the Star Chart opens. Land on the moons and the other planets of your system, then drive to other stars. Out there are black holes that bend the light, dying stars that fill the sky, and pulsars sweeping their beams. Every world is a planet of its own, down to its core - and none is a copy of home: each has its own plants and woods, its own animals, new elements to find and its own monsters. On Phaton the rain is acid and the cave pools burn: you'll need a suit made from its own crystals to survive there.

Runs on anything

From a phone to a gaming PC.

A quick check on the first run picks settings that suit your device and runs on its best graphics card, from a light mode for older phones to crisp sun shadows, soft ambient occlusion, light shafts and storm-tossed seas with wakes and raindrop rings on a gaming PC. Touch controls, keyboard and mouse, or a controller: switch any time.

There is nothing to install and nothing streamed from a data centre: the whole game runs on your own device. Dig to the core of a planet, sail its seas, fly into space and step through gates to other universes, all in one game, in a web page, on a computer or a phone.

Afternoon sun through the red canopy of Emberwood — Afternoon sun through Emberwood, as it looks in the game