Grow an asteroid. Become a black hole.
A free space game in your browser. Pull in matter with gravity and climb 22 classes, from a tiny rock to a galaxy-scale horizon, while rival worlds race you for the same matter.
No download. Any browser.
Twenty-two classes between a rock and the horizon
Every capture adds mass. Five times your mass is a new class, and each one plays differently.
Dwarf planet
New mass class · 4 of 22
Rubble pulls itself into a ball. Smaller fragments start to fall into orbit around you.
≈ 9.38 × 10^20 kg
Super-Earth
New mass class · 7 of 22
Oceans, clouds and enough pull to hold on to moons of your own.
≈ 5.00 M⊕
Gas giant
New mass class · 8 of 22
Banded storms, a ring system and a family of captured moons.
≈ 1.00 M_J
Sun-like star
New mass class · 11 of 22
Fusion ignites. Planets and asteroid belts settle into orbit around you.
≈ 1.00 M⊙
Black hole
New mass class · 16 of 22
The core collapses. Matter falling in lights up a glowing accretion disk.
≈ 200 M⊙
Galactic core
New mass class · 20 of 22
Stars and whole galaxies spiral in, on the way to the Interstallar at the edge of the universe.
≈ 100,000,000 M⊙
- Your mass and classHow heavy you are, and how far to the next class.
- Threat warningA bigger rival is close. Build sideways speed, then burn away.
- Rival worldsComputer-controlled worlds racing you for the same matter.
- Your star systemAs a star, keep planets, moons and belts on stable orbits.
- Flight notesShort tips for the moment you are in.
- ToolsWeapons, mining drones and lasers, unlocked as you grow.
- Local scanFood in mint, threats in coral.
How to play
Drift close to anything smaller than you and it falls into orbit and merges. Keep clear of anything bigger. Tap the markers on the screenshot to see what each panel does.
| Fly | W A S D or the arrow keys |
|---|---|
| Brake | Shift |
| Boost | Space, once you unlock it |
| Survive | Build sideways speed, then burn away from bigger bodies |
| Evolve | Spend adaptation points and cross each mass threshold |
| Controller | Left stick to thrust, A to burn, B to brake |
| Touch | Drag to steer, a second finger to burn |
| Pause | Esc |
What you do on the way up
The game tells you as it happens. These are moments you will see.
Gravitational capture
Smaller bodies fall into orbit and merge. String quick captures into chains.
Rival worlds
Rivals grow beside you, steal matter and hunt you once they outweigh you. For your first 90 seconds they keep away.
Apex rivals
The Shale Tyrant, the Ember Leviathan and the Hungry Dark wait at moon scale, as a red dwarf and as a black hole.
Star system
As a star, keep planets, moons and belts on stable orbits and stop your worlds colliding.
Space weather
Meteor showers to chase, gravity waves to brake through, radiation storms to escape.
Life Lab
Collect water and DNA, hatch companions and name them. Each one changes how you play.
Engineering
Launch mining drones and lasers, aim weapons and fleets, and turn raw ore into upgrades.
Supernova
Massive stars can explode. Black holes grow disks and reach for the Interstallar.
Daily challenges
Three new goals every day, the same for everyone. Meet all three to keep your streak.
Share a universe
Every universe has a seed. Replay a great run or send a friend the same sky.
Play your way
Rebind keys, scale text, raise contrast, reduce motion and pick an interface theme.
Questions
What is Anti-Horizon?
Anti-Horizon is a free space game you play in a web browser. You start as a tiny asteroid, pull in smaller bodies with gravity and grow through 22 mass classes, becoming a planet, a star, a black hole and finally the Interstallar, while rival worlds race you for the same matter.
Can I play with friends?
Yes. There are two public multiplayer arenas of up to 200 pilots each, and Quick play drops you into the busiest one. Playing online needs a free account.
How do you finish the game?
Keep growing until you reach the Interstallar, the final mass class, class 22 of 22. Each class needs five times your mass, so a run climbs from a rock to a galaxy-scale horizon.
Does it run on a Chromebook or a slow computer?
Yes, it runs in the browser with nothing to install. The Performance setting goes from Ultra down to Lowest, and Lowest is the simplest and smoothest level, made for Chromebooks and older devices.
Is Anti-Horizon free?
Yes. Anti-Horizon is free to play, with no ads and no purchases. In-game resources have no cash value.
Are there leaderboards?
Yes: this week’s biggest journeys, the fastest black holes, and a board for the universe everyone shares each day. Anyone can look; sign in and your journeys join them.
Do I need an account?
No. You can play straight away as a guest, but guest journeys are not saved. A free account lets you save, continue and play online: continue with Google or with your email address, and we email you a six-digit code to confirm it is you. You stay signed in on that browser for 30 days.
Where are my saves kept?
Once you sign in, in your browser, in three save slots. Guest journeys are not saved. If you sign in with Google you can also save to a private app folder in your own Google Drive and load it on another device.
What devices does it run on?
Any recent desktop or mobile browser, such as Chrome, Edge, Firefox or Safari. It plays with a keyboard and mouse, a game controller or touch, and lowers its own graphics on slower devices.
Can I change how it plays?
Yes. Rebind keys, scale text, raise contrast, reduce motion and pick an interface theme from the game’s settings.
Is the astronomy real?
It is inspired by real astronomy and simplified for play. The in-game Field Guide explains each class, and the sources page lists the science behind it.
What is accretion?
In astronomy, accretion is how objects grow by pulling in surrounding matter with gravity. Planets, stars and black holes all grow this way, and so do you in Anti-Horizon.
The Interstallar
Final mass class · 22 of 22
A final horizon at the edge of the universe. Every black hole started as a rock, and yours starts now.
Play free