ANTI-HORIZONUse gravity to capture matter, compete with computer-controlled rivals, and evolve into a star or black hole. Play with keyboard and mouse, a controller or touch. Your progress saves in this browser.
Move gently through the nearby field.
Your gravity will bring smaller fragments into orbit.
Your horizon has joined the distant signal. Light traces a single boundary now. Beyond it, there is still space to cross.
The merger and its mass are saved once. Continue gathering, explore, or begin another expedition from the existing menu.
Each slot has its own universe, companions, resources and records. Switching saves your current journey first.
On: checkpoint after three new astronomical classes. Off: checkpoint every 15 seconds. Pets, resources and the universe save together. Closing between checkpoints restores the last saved state. Save now or Save & return to main menu keeps everything immediately.
Charted sectors remember visits and extracted matter. Dim sectors show estimated density. Rival markers record their last observed position, not live tracking. Coordinates use scale-relative travel.
All original and selected-path classes, scaled mass editing, test bodies and resources affect only this sandbox. Journey saves, achievements and records stay separate. Experimental planets are released on physical trajectories and can escape or collide.
Choose The Interstallar above for a merger test. These buttons position the persistent landmark in this sandbox only.
Amount uses the same unit as the current flight mass readout. Removing mass cannot go below the initial asteroid. The selected journey stays selected.
Speed 1 is approximately circular. Above 1.42 usually escapes. The physical body budget still applies. AP is capped at 100, other resource limits remain in force.
Simulation paused. Pan and frame the current scene. PNG export excludes the interface.
Journey slots, Sandbox, Boss gauntlet and Salvage expedition have separate progress. Multiplayer is a live arena and does not write journey records.
Five public arenas of up to 100 pilots each: the same asteroids, growth and combat, all run by the server. About one in ten new bodies is a coin worth 15; spend coins on hats and shades.
Checking the arenas…
Not connected.
Live matches keep running while a menu is open. Text and any media you send are shared with the room. Shared media is hidden unless enabled in Settings.
T opens signals. Y sends your first saved taunt. Signals last five seconds, with a three-second cooldown. Nearby rivals answer during offline play.
Choose text, a local image or GIF, or both. Four saved signals. No remote image URLs. Maximum 96 KB per image.
Inspect captured bodies, orbit stability and collision risks.
Your universe is paused. Take your time.
Your journey is saved automatically on this browser.
Collide with blue-marked icy asteroids to collect water. Mint-marked rocks contain scarce DNA: one sample per discovery. Use 500 water and 100 DNA in the discovery wheel to place a companion egg in incubation. Then fly while it develops.
Common 59% · Rare 35% · Epic 5% · Legendary 1%
Common includes the 14 existing Uncommon companions. Each spin selects an undiscovered pet in its sector. Completed sectors cost nothing. No purchases or cash value.
Up to 24 characters. Press Enter to save. Leave blank to use the original name.
Wheel odds are shown above; a full incubator blocks further spins. Only the equipped pet grants its listed thrust, gravity and collision-defense bonuses. All companions also extend life-signal detection. Collection and eggs carry across journeys within the selected save slot. These imagined organisms are science fiction.
Choose an action, then press the key you want for it. A key already in use swaps places. Arrow keys always steer too. Escape cancels.
These switches freeze decorative motion only. Orbit physics, gas consumption and gameplay keep running. Reduced Motion overrides all of them.
For a Chromebook, try Eco CPU, shaders Off, Low gas, Low textures and 720p or 540p. Resolution affects the game canvas; menus stay sharp.
WASD or arrows apply thrust. Release to coast. Hold Shift to brake. Momentum matters: move slowly through a field to let gravity work.
Smaller objects curve toward you. Early captures spiral inward. At star scale, suitable trajectories can settle into stable orbits. Absorb bodies below about 63% of your simulation mass; similar bodies bounce and fragment.
Red markers indicate larger bodies. Build sideways velocity for a slingshot, then thrust outward. Large impacts damage cohesion; it regenerates after six quiet seconds. Hardcore caps cohesion at 50% and makes worlds scarcer as you grow. Rare cache-marked bodies carry extra DNA, water and Raw Material; collect them through contact or inner absorption.
Each major evolution grants one point. Press U for three stackable choices. Unlock Space for escape burns, E for a gravity pulse, and Q for amplified gravity.
U opens original adaptations, costing 1 AP each. K opens the connected engineering trees, which spend Research Points. X aims weapons, Z assigns mining drones, I aims your personal Mining laser. Hold click to fire or cut; click in drone mode to issue an order. T opens quick signals; Y sends your first saved signal. Edit signals from the T panel.
Use Game modes for Boss Gauntlet, Salvage Expedition, Sandbox or the optional shared arena. The scenario modes use separate saves. The bottom of Settings contains resolution, CPU, shader and FPS controls, with 240 FPS followed by Unlimited.
At star scale, coast to preserve planets. Hold O for orbital paths. Tab toggles a wide system view; click a planet to select it. L opens the observatory. C collapses the selected orbit over time. Gas disks condense into planetesimals. Black holes collect matter in a disk before gradually accreting it. Seek nebulae and dense galactic arms.
Look for H₂O and DNA markers on icy asteroids. Physical contact collects the marked resources once. Tidal breakup preserves them in the stream; collect them when it reaches your inner accretion region. A passing or escaping stream awards nothing. Press N for Life Lab. Use the discovery wheel to obtain an egg, spend 20–180 seconds in flight, then return to hatch it. Equip one of 50 companions to extend life-signal detection. Your collection survives new journeys. Equip a companion to give it a saved nickname in the Life Lab. Press H during flight to hide or restore the HUD and notifications; Escape still opens the pause menu.
Equipped companions grant rarity-based thrust, gravity and collision protection, listed in the Life Lab. Choose one of three save slots from the main or pause menu. Its toggle saves your journey every time you reach a new class; turn it off to also autosave every 15 seconds. Save now also keeps all progress. Companion size is adjustable in Settings or the Life Lab.
Press G to chart visited sectors and plot a course; V opens the latest recorded encounter. P pauses the universe for a photo with local PNG export. Equipped companions develop permanent evolution branches in Life Lab. At star scale, the observatory shows composition, climate and established period relationships. Flare forecasts give twelve seconds of warning before a moving physical wave. Sandbox has its own save and never updates journey records.
Flight notes show an optional journey goal for your current class. Complete one per class to earn a banked adaptation point. Goals measure real captures, exploration, stable systems or accreted mass. No water, DNA or pets are awarded. Press J for a connected advancement catalogue with six branches. Earned milestones display framed plaques with task, goal or challenge chimes. Settings can disable the notifications or move them below your system. Records and the journey log remain in the Archive. The Archive keeps your latest discoveries and goals. Different fields have their own shapes and drift; the galaxy chart shows richer routes.
Ordinary stellar classes share scale-relative movement. Selected journeys keep ordinary stellar movement until their remnant stage, when the stated speed multiplier activates. Press 1–8 to hide or restore individual HUD instruments: mass, rivals, radar, system metrics, telemetry, flight notes, and abilities. Press ` to minimize the open window and return to flight. Press F to open the dock. It never opens on hover, and hides after five idle seconds, when the pointer leaves, or when you open a window. Reopen windows there, or press their usual N, L, G, U, V, or P shortcut again to toggle them. H still hides the full HUD. U opens the deterministic engineering tree. Use its branch tabs and plus buttons; all costs and prerequisites are visible.
The old random choices have become a deterministic tree. Earn one adaptation point at halfway and one at the end of every evolution bar. Points are banked before Moon scale, when the five main branches open: Mining, Science, Attack, Defense and Speed. Mining starts free: install Orbital Outpost for a station and one drone. Drones travel to intact rocks, cut them apart, and carry finite Raw Material home. Shots and mining fracture real mass into recoverable debris; ore is not regenerated by rebreaking it.
Science: spend 25 Raw Material to build the Research Centre. Each powered batch consumes 50 Raw Material and returns one Research Point after 18 simulated seconds. Installed research and power upgrades shorten that time. Most ranks cost one adaptation point plus one Research Point. From rank three, or after ten powered research minutes, they cost two Research Points. Every row lists prerequisites and shows installed ranks. Science unlocks the other branches, advanced mining, optics, sample recovery, stellar engineering, Energy and Cosmetics.
Attack builds turrets that prioritize rivals and otherwise fracture ore-bearing rocks. Optics and two turret ranks unlock attack lasers; mining lasers require an installed attack laser, two Mining Fleet ranks and Drill Assemblies. Defense adds shielding and existing damage reduction. Speed adds thrusters, counter-thrust, braking and the Space boost. All installations add visible modules to your body or station, including stellar and remnant forms.
Energy: build closed-cycle turbines, fission reactors, fusion reactors, stellar collectors and Dyson swarms in sequence. Batteries store surplus power in Balanced mode. Charge mode diverts generation from mining, research, weapons and shield recharge; ordinary flight still works. Fleet Overclock spends stored power to speed up all powered equipment together. Short duration means higher intensity, up to 2.5×; flight gains at most 25%. Both sliders show the actual available-battery tradeoff. Timers stop in menus. Cosmetics adds decorative follower worlds with a visibility toggle; they carry no physical mass or capture bonuses.
The observatory has five optional Blueprints. Assemble planets, moons, belts and period relationships through real captures, then coast through the uninterrupted hold. First completion earns the Architect crest. Survived impacts leave a capped history of craters or fractures; gas worlds show disturbed bands, and stellar bodies retain the record as plasma or disk imprints.
Appearance lets you select earned body markings, companion accessories; Settings holds the unified interface theme. These have no gameplay bonuses. After reaching star scale and completing four different class journey goals in one run, Expeditions lets you retire your body and begin as an asteroid with an optional harder promise. Companions, eggs, resources, achievements and cosmetics carry over within the slot; your old body, orbits and adaptations retire. Rank rewards commemorate the journey without increasing your power. Ready eggs now open in a short reveal showing the actual creature, with a distinctive legendary sequence. Reveal companion skips to the result. Reduced motion displays it immediately.
At Massive Star, CHOOSE PATH unlocks in flight and pause. Selection keeps your current star, mass, momentum, health, adaptations and partly filled growth goal. Future stages follow your selected journey. Singularity: Contracting Supergiant, Collapsing Core, then Singularity and the existing black holes. Nebula: Mass-shedding Star, Expanding Stellar Shell, then Emission Nebula, Molecular Cloud, Stellar Nursery and Galactic Nebula. Neutron: Compressed Stellar Core, Proto-neutron Core, Small Neutron Star, Magnetar, then Strange Matter. Gravastar: Dense Shell Star, Vacuum-transition Core, then Compact, Vacuum and Cosmic Gravastar. A later starting star retains its current form.
Each new class requires five times the previous threshold. Revise a choice while still at the starting star stage; the first branch evolution locks it. EVOLUTION PATH then shows the reached and upcoming stages. Supernova and special abilities arrive when the first remnant is reached, after the two precursor classes. Singularity doubles gravity and moves at two-thirds speed. Nebula has no gravity and slowly dissolves overlapping matter. Neutron stars gain 35% speed; Magnetar adds 50% gravity. Strange Matter gains a conversion field and 25% speed. Gravastars gain 25–60% gravity and 40–55% collision protection, moving at 90% speed. The actual supernova impulse can disturb nearby orbits. Ignoring the choice keeps normal stellar growth through Stellar Colossus. These compressed transitions retain mass and do not model real stellar mass loss.
Each black-hole class has its own procedural silhouette: ember lanes, a tilted copper vortex, polar jets, a golden torus, a galactic maelstrom, a quasar crown and the Interstallar. Bright knots travel around the disk; inner lanes turn faster. Stored captured matter controls gas brightness and jet activity. Faint returned-light arcs can appear without stored matter. The Interstallar has separate moving outer filaments. Pause and Photo freeze all flow; Reduced Motion holds the optional paths still, and Performance lowers their detail.
The Interstallar is the final evolution after the ultramassive black hole. Its pale inner ring and amber outer disk carry moving filaments; inner lanes turn faster. Anti-Horizon brightens the flow. Your mass can keep growing after the final class. Reduced motion holds the rings still, and pausing or taking a photo freezes them. To inspect this class immediately, use the separate Sandbox and press B for experiments.
Inspired by astronomy, designed for play. Mass labels follow astronomical landmarks; size, time, distance, and mass ratios are compressed. The camera locks to your interpolated body position; R recenters it and resets zoom. A dotted line forecasts unpowered flight. The original circular endpoint stays inside the screen; an amber cross warns of projected contact. Sources are assumed to keep their current velocity, so the forecast is an estimate. It begins at your rendered body and uses the same gravity softening as flight physics. Hold O during flight for faint orbit ellipses around bodies already on screen, and select a body to see its PERI and APO markers drawn in place. M⊕ = Earth masses · M_J = Jupiter masses · M⊙ = Solar masses.
Actual black-hole forms can discover a distant persistent horizon. Follow the gold marker or press G to plot its course; 8 hides its approach instrument. Beacon, lens, disk and photon zones lead to an irreversible inner-flow warning. Turn outward early with full thrust; Shift brakes. Defense and emergency shell still work. An early black hole cannot merge.
At The Interstallar or greater black-hole scale, slow below 38 scale-relative units per second between 1 and 3 shadow radii and hold for 1.5 seconds. The protected merger takes ten active, visible seconds; Escape pauses it. The two masses combine once, then flight continues. Charting and completing make explicit checkpoints. Sandbox placements award no journey advancements. In Photo mode, choose 1× or 2× export; PNG width is capped at 3840 pixels.
Press G after reaching star scale and choose Join encounter. Four phases last thirty minutes each, counted only during visible active flight. Follow the bridge course to gather its finite gas and condensed worlds. Completion banks three adaptation points up to the 100-point cap, increases gravity by 10% and gas intake by 20% for this journey. Its clock is saved every minute without changing your chosen flight checkpoint cadence. FPS in telemetry measures rendered frames over half a second. Hidden tabs are excluded. Reduced Motion freezes decorative galactic rotation.
Choose at Massive Star or a later stellar class. Keep your current star, mass, movement, adaptations, companions and saved universe. Future growth follows the selected stages instead of the normal stellar sequence.
Change your choice while you are still at the starting star stage. The first branch evolution locks it for this journey. Every new class requires five times the previous threshold. Supernova and remnant abilities activate only when the remnant stage is reached. Strange Matter and gravastars are speculative fictional gameplay forms.
Select one adaptation. Each choice becomes part of this journey.
All powered machinery runs faster. Flight gains at most 25% speed. Charging pauses machinery; ordinary flight still works. Pausing stops all timers.
Decorative worlds carry no mass and never count as captured planets.
Physical mass leaves your core and enters an orbit. Guardians shield you only while stably bound. Ejection, collisions and mass loss can remove that protection.
Select a badge to inspect it. Tab and arrow keys navigate the map. Connections guide your journey; milestones are earned independently. J opens or minimizes this window during flight.
Choose a body marking and companion accessory. Settings holds one interface theme for your HUD, menus, dock, charts and advancement plaques. Earn them through achievements or commemorative expeditions.
Retire a completed stellar journey and return as an asteroid. Keep a record of what you built, unlock commemorative looks, and choose a harder optional promise.
Your companion is already safely recorded. Closing or skipping the reveal never changes its rarity or awards a second creature.
A space evolution game with offline journeys, scenario modes and an optional private multiplayer arena.
Black holes in this game are an original real-time rendering inspired by published scientific visualisation. No film footage, images or sound are included.
Every surface, nebula, star, particle, and sound is generated locally. No external art, music, fonts or runtime libraries. Offline modes make no network requests. Optional multiplayer connects only to the server address you enter, and optional Google sign-in contacts Google only when you use it.
Built with JavaScript, Canvas 2D, CSS, and the Web Audio API. See the sources and implementation notes for the scientific references and local source files.
Mass labels use astronomical reference points. Distances, elapsed time, growth rates and gravitational interactions are compressed for gameplay. Companions are fictional lifeforms.
Privacy policy · Terms and conditions · Source license
© 2026 AK
Version 7.8.1 · Console · Full source included · MIT licensed
Desktop keyboard and mouse recommended.
Every journey's starting universe grows from one seed. The same seed always builds the same universe; what happens next is up to you. Share a code to let a friend fly your universe: they get the same one on the same difficulty and CPU budget.
Every class of body you reach or meet on a journey is recorded here, with a note from real astronomy. Sandbox flights do not count.
Sign in to save your journeys and play online. Use Google or your email; every time, we email you a 6-digit code to confirm it is really you.
Enter the 6-digit code we sent to . It expires in 10 minutes.
Not now? Back keeps you flying. Leaving ends this journey without saving it.