About the game
Blob Arena 3D is the .io growth brawl rebuilt in WebGL with Three.js. Instead of flat discs you get real spheres: a translucent shell with a glowing core floating inside it, sitting on a walled arena plate with a sun that drags a genuine shadow under every blob. The camera trails you from a steep three-quarter angle and pulls smoothly back as your mass climbs, so the moment a rival stops being a snack and starts being a threat is something you see rather than read off a number. Nothing is downloaded — every mesh is built from sphere, cone and box primitives at load time, the 420 pellets and the nine spike balls are each a single instanced draw call, and every name tag is painted on a canvas in the browser.
Underneath the lighting sits exactly the game the 2D Blob Arena was. Radius is 3.4 × √mass, so doubling your mass only makes you 41% wider. Speed falls off as 240 × (18/r)^0.38, so growing costs you agility but never enough to make escape impossible. You need to be 14% heavier than someone and actually sitting on top of them to swallow them, you keep 92% of what you eat, and above 320 mass a full 1% of the excess rots away every second — which is why the score is the biggest you ever got, not the mass you happen to be holding when someone finally catches you. Fifteen AI rivals share the same rules, each with its own appetite and its own nerve, and they hunt, flee and lead their targets instead of drifting.
How to play
- Desktop: move the mouse — your blob steers towards the pointer, and the further out it is the harder it pushes. Arrow keys or WASD work too.
- Mobile: drag anywhere on the arena. A virtual stick anchors itself wherever your finger lands.
- Nothing can eat you until you make your first move, and for 2.5 seconds after it. Your blob flickers for as long as it is untouchable.
- Press Space or Enter to start a new run after a game over; Pause freezes the whole arena.
- Tap the ⛶ button for fullscreen — the 3D view scales to the whole screen.
- On the minimap, a red dot is a blob heavy enough to swallow you and a grey dot is not. The white box is what your camera can currently see.
Rules
- Your radius is 3.4 × √mass. Mass is what decides every fight; radius is only how much of the arena you cover.
- The bigger you are the slower you move — speed is 240 × (18/r)^0.38, with a hard floor of 62 — but even a maximum-size blob keeps 42% of the top speed, so nobody is ever truly safe.
- To swallow another blob you must be at least 14% heavier than it AND overlapping it deeply enough that its centre is inside you. Brushing past a smaller blob does nothing.
- You keep 92% of a victim's mass. A pellet is worth a flat 2 mass no matter how big you are, so pellets are an opening move, not a strategy.
- Above 320 mass, 1% of the excess rots away every second. The leader shrinks while it sits still.
- The green spike balls are harmless below 260 mass — they are a small blob's fortress. Above it they cut you to 72%, and never below 208.
- Fifteen AI rivals play by the same rules, each rolled with its own aggression (0.55–1.35) and caution (0.7–1.5), so some commit to a chase that others abandon.
- A dead rival respawns after one to two seconds somewhere far from you, sized against your current mass: sometimes fodder, sometimes a peer, sometimes a predator that can eat you outright.
- Your score is the largest mass you ever reached during the run, so decay can never quietly eat a good result.
- The camera pulls back as you grow and stops widening once you are big enough to see most of the arena at once.
Strategy & tips
Hunt the 14%, not the bigger number
You cannot swallow a blob that is merely smaller — you need to be 14% heavier, and you need its centre inside your body. A rival at 90% of your mass is not prey, it is a stalemate, and every second you spend circling it is a second a real predator uses to close in. Pick targets you outweigh by a third or more and the kill is over in one pass.
Small is fast, so start by being greedy
At the starting mass you move at nearly top speed and roughly half of the opening field is already edible. That first half minute is the cheapest mass in the game: charge the little ones instead of grazing on pellets, because a 20-mass kill is worth ten pellets and takes a fraction of the time.
Park on a spike when a giant closes in
Spike balls do nothing to you below 260 mass, and the AI actively steers around them once it is heavy enough to pop. That makes every spike a fortress a small blob can sit inside while a monster orbits helplessly outside. Learn where the nine of them are from the minimap early, because you will need one later.
Read the minimap, not the blob in front of you
The camera pulls back as you grow, which makes nearby rivals look smaller exactly when they are getting more dangerous. The minimap does not lie: red means it can swallow you right now. If two reds are converging on you, break away before they close the gap, because a full-speed chase is decided by who turned first.
Once you lead, keep moving and keep eating
Above 320 mass you are rotting at 1% of the excess per second, so a leader who parks in a corner is quietly handing the run back. Keep sweeping pellet clusters even when they feel worthless — the point is not the 2 mass, it is that the arena replaces pellets where you are not, so the AI grows in the space you abandon.
Cut the corner on a fleeing rival
The AI leads its targets and flees the moment you cross the 5% threat line, which is well before you can actually eat it. Chasing it in a straight line never works: it is only slightly slower than you. Push it towards a wall instead, and take the inside line when it turns — the arena boundary does the cornering for you.
FAQ
Is this really 3D, or a 2D game with a 3D look?
It is real 3D. The scene runs on WebGL through Three.js with a perspective camera, a directional sun writing into a shadow map that follows your blob, hemisphere fill light, distance fog and a gradient sky dome. Every blob is an actual sphere with a translucent shell and a separate glowing core mesh inside it, and the shadow you see under it is a genuine shadow-map shadow, not a painted disc.
Why can I not eat a blob that is clearly smaller than me?
Two things have to be true at once. You must be at least 14% heavier — a blob at 90% of your mass can never be eaten, only outrun — and its centre has to be deep enough inside your body, specifically within your radius minus 35% of its own. That second rule is why a glancing pass does nothing: you have to actually swallow it, not bump it.
Why is my mass falling when nothing is attacking me?
Everything above 320 mass rots at 1% of the excess per second. It is the only thing that stops a runaway leader from becoming unkillable, and it is why the score is the biggest mass you ever reached rather than the mass you die holding. If you are shrinking, you are not eating enough — decay is roughly the value of one pellet per second once you are past 520.
Are the green spike balls worth going near?
Below 260 mass they cannot hurt you at all, which makes them the best hiding place in the arena: anything big enough to eat you is also big enough to pop on them, and the AI steers well clear. Above 260 they take you down to 72% of your mass, so once you are a genuine contender they become the one piece of terrain you have to plan around.
Do I need to download or install anything?
No. The game is a single ES module that loads a local copy of Three.js from this site. There is no plugin, no app store and no account — it runs straight in the browser tab, and it works offline once the page has been cached.
My browser says it cannot run the game, or my phone looks softer than my desktop.
The game needs WebGL; if you see a message instead of the 3D view, update to a recent Chrome, Edge, Firefox or Safari or enable hardware acceleration. On small screens the game drops antialiasing, halves the shadow map and uses a lower-poly sphere — the arena size, the pellet count, the fifteen rivals and every rule stay exactly the same, only the drawing budget changes. The 2D Blob Arena on this site plays fine without WebGL.
