Free idle game · the real elements

Forge the universe, atom by atom.

Start with a single hydrogen atom. Synthesize your way through all 118 elements, build real moons, planets and stars, and collapse it all in a supernova to come back stronger.

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FreeNo downloadNo account neededPhone or computer

A glowing atom at the center of a galaxy, circled by element tiles

118real elements to collect

30moons, planets, stars and galaxies to build

49real molecules to synthesize

96real spectra to identify

Elements

Start with hydrogen. End with oganesson.

Spend energy to synthesize atoms. Every element feeds the one below it, so your chain grows while you watch, and keeps earning while you’re away.

Elements arrive in the order they’re common in Earth’s crust
Every 25 atoms of an element double its output
Facts about every element in the Catalog

The Elements screen: osmium and gold cards with their atoms and energy

Supernova

Collapse it all. Come back stronger.

When a cycle has released enough energy, trigger a supernova for stardust that multiplies everything. Later, neutron stars collide in kilonovas, and dark matter opens the deep sky.

Stardust, neutrons and dark matter, each stronger than the last
Permanent upgrades bought with isotopes
Levels and a weekly leaderboard

The Stars screen: supernova and kilonova panels

Cosmos

Build the Solar System from your leftovers.

Surplus atoms become real worlds: the Moon, Mars, Jupiter, Halley’s Comet. Then build the Sun, a pulsar and whole galaxies, each with its own bonus and its own page of real science.

A living orrery of everything you build
Send probes to your worlds for rare specimens
Comets, meteor showers and solar flares while you play

The Cosmos screen: an orrery of the Sun with planets and moons

Spectroscopy

Read the light of the stars.

Every element glows at its own colors. Name the element behind a star’s spectrum, using real lines measured by NIST. Get them right and time itself speeds up.

Moving stars, starlight and mixtures unlock as you progress
Know an element by heart and its lab spectrum disappears
Complete a family in your Spectra collection for a permanent bonus

The Spectra screen: a star's emission lines and four element choices

The periodic table

All 118 elements, all in the game.

Hover or tap an element to read about it. In Nucleo they arrive in the order they’re common in Earth’s crust, so oxygen comes first and oganesson last.

Swipe the table sideways to see all of it.

Facts from the Nucleo Catalog. Crust abundances are typical values in parts per million.Collect them all →

And while it ticks

Always something to do.

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Chemistry

Combine surplus atoms into 49 real molecules, from water to caffeine, for permanent bonuses.

🛰

Probes and specimens

Send probes to the worlds you’ve built. They bring back meteorites, comet dust and presolar grains.

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Daily research

Three small goals every day. Keep a streak for a bigger energy bonus.

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Mastery and achievements

121 achievements, five mastery stars per element, and titles to show on the leaderboard.

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Cosmic events

Catch comets as they streak past, and make the most of meteor showers and solar flares.

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Play anywhere

Install it on your phone like an app. Move your progress to another device with a backup code.

Optional · Enjin

Collectible cards, with bonuses in the game.

Nucleo has a collection of cards on Enjin: the element families, the Sun, Jupiter, the Crab Pulsar, Messier 87 and more. Hold them in your Enjin Wallet, sign in, and each one gives its bonus in the game. Your wallet also keeps your progress, on any device.

View the collection on nft.io ↗

Entirely optional: the whole game is free to play without a wallet or any card.

Nucleo Genesis card — **Genesis**Energy ×1.5

Crab Pulsar card — **Crab Pulsar**Rays +50%

Noble Gases card — **Noble Gases**Family +25%

Messier 87 card — **Messier 87**Dark matter +25%

13.8 billion years in the making

The universe is waiting.

Your first hydrogen atom is one tap away. Free, in your browser, no account needed.

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