Arena API

A mod registers handlers for events and calls these functions inside them. Nothing else exists in the sandbox — no network, no files, no clock, no page. Every number is clamped by the engine. There is no energy bar: each key cools down on its own, by what pressing it did — every call that changes the world adds its cooldown to that key, calls made in one press add up (to at most 15 s), and your code cannot change any of it.

Power: one mod carries at most 60, a loadout of three at most 100. A handler may run for 3 ms, and a mod may spend 30 ms of CPU each second. One push moves another player at most 16 m/s.

Events — when your code runs

Call	What it does	Cooldown	Power
`onAbility(fn(me))`	Runs when the player presses this mod’s key (Q, E or R, by slot).	—	—
`onAbilityHold(fn(me, dt))`	Runs ten times a second while the key is held.	—	—
`onAbilityRelease(fn(me, heldSeconds))`	Runs when the key is let go.	—	—
`onTick(fn(me, dt))`	Runs ten times a second for the whole match. Keep it light.	—	—
`onHit(fn(me, other))`	Runs when something of yours hits a player, or a player bumps into you.	—	—
`onHurt(fn(me, from))`	Runs when you are knocked by somebody else.	—	—
`onLand(fn(me, fallSpeed))`	Runs when you land on the ground.	—	—
`onJump(fn(me))`	Runs when you jump.	—	—
`onRespawn(fn(me))`	Runs when you come back after falling out.	—	—
`onRoundStart(fn(me))`	Runs once when the match starts. A good place to set your looks.	—	—
`onCoreGrabbed(fn(me, byId))`	Runs when anybody picks up the Core.	—	—
`onRingFall(fn(me, ring))`	Runs when a part of the map starts to fall: ring is its index in the fall schedule (0 the stepping stones, then the Garden, the West Ruins, the City, the Temple, the Plaza's edge, the Plaza shrinking).	—	—

Your body

Call	What it does	Cooldown	Power
`self.push(vector)`	Push yourself. Up to 14 m/s.	0.75s	8
`self.dash(direction?, power?)`	A burst along your look direction (or one you give). Up to 18 m/s.	1.25s	12
`self.jump(power?)`	Jump, even in the air. Up to 14 m/s.	1s	10
`self.hover(seconds)`	Float with gravity switched off. Up to 3 s.	6s	12
`self.setSpeed(multiplier, seconds)`	Run faster or slower (0.4×–1.8×) for up to 8 s.	6s	12
`self.setGravity(scale, seconds)`	Fall slower or faster (0.15×–2.5×) for up to 8 s.	6s	12
`self.setScale(scale, seconds)`	Grow or shrink (0.6×–1.6×) for up to 8 s. Bigger is heavier.	8s	12
`self.setInvisible(seconds)`	Become a faint shimmer for up to 3 s.	10s	14
`self.shield(seconds)`	Nothing can move you for up to 1.5 s.	12s	16
`self.rollback(seconds)`	Rewind yourself to where you were up to 3 s ago.	12s	20
`self.drop()`	Let go of the Core.	—	—

Making things

Call	What it does	Cooldown	Power
`spawnProjectile({ from?, direction?, speed?, look?, color?, size?, push?, gravity?, effect?, lifetime? })`	Fire something. It pushes whoever it hits; `effect` can be "burn", "freeze", "slow" or "pull".	0.9s	14
`spawnBeam({ from?, direction?, range?, color?, push? })`	An instant line that pushes the first player it touches. Up to 30 m.	1.5s	16
`spawnWall({ at?, width?, height?, seconds?, look? })`	A wall in front of you that blocks people for up to 8 s.	5s	10
`spawnRamp({ at?, length?, seconds? })`	A ramp to launch off, for up to 8 s.	5s	8
`spawnPad({ at?, power?, seconds? })`	A jump pad anybody can use, for up to 8 s.	5s	8
`spawnZone({ at?, radius?, effect, seconds?, color? })`	An area that burns (pushes out), freezes, slows, makes slippery, or lifts whoever stands in it.	6s	16
`spawnDecoy({ at?, seconds? })`	A copy of you that stands still and fools people.	8s	8
`spawnOrb({ at?, size?, color?, bounce? })`	A heavy ball you can roll into people. Up to 3 at once.	3s	10
`spawnVehicle("car" \| "train" \| "board", options?)`	A car you drive, a train that crosses the arena on a straight track, or a hover board. Vehicles push people out of their way.	20s	30

Forces and fields

Call	What it does	Cooldown	Power
`applyForce(targetId, vector)`	Push one player or object. Up to 16 m/s.	1s	14
`pullTowards(point, strength, radius)`	Pull everything nearby towards a point. Use it in onAbilityHold to keep pulling.	0.15s	14
`pushFrom(point, strength, radius)`	Shove everything nearby away from a point.	2s	16
`createGravityField({ at?, radius?, scale, seconds? })`	An area where gravity is weaker or stronger, for up to 8 s.	8s	14
`createWind({ at?, radius?, direction, strength?, seconds? })`	A gust that keeps pushing one way, for up to 8 s.	8s	14
`freeze(targetId, seconds)`	Stop a nearby player in place for up to 1.2 s.	10s	18
`slow(targetId, factor, seconds)`	Slow a nearby player down (down to 0.35×) for up to 3 s.	6s	12
`chain(targetId, seconds)`	Tie a nearby player to you, pulling them in for up to 2 s.	10s	18

The world

Call	What it does	Cooldown	Power
`terrain.raise(point, radius, height, seconds)`	Lift the ground for up to 6 s.	8s	12
`terrain.lower(point, radius, depth, seconds)`	Sink the ground for up to 6 s.	8s	12
`terrain.ice(point, radius, seconds)`	Make the ground slippery for up to 6 s.	6s	10
`terrain.bridge(from, to, seconds)`	A temporary plank between two points, up to 18 m.	6s	10
`terrain.crack(point, radius)`	Drop the tiles under a point for 4 s. They come back.	12s	18
`world.query(radius)`	What is near you: players, the Core, orbs, vehicles and projectiles. Read-only.	—	—
`world.players()`	Every player still in, with position and score. Read-only.	—	—
`world.core()`	Where the Core is and who holds it. Read-only.	—	—
`world.time()`	Seconds left in the match. Read-only.	—	—
`world.groundAt(point)`	The height of the ground under a point, or null over the void. Read-only.	—	—

Looks and sound

Call	What it does	Cooldown	Power
`setWeaponModel({ parts: [{ shape, size, offset?, rotation?, color, emissive?, metal?, rough? }] })`	Redesign what you hold, from up to 24 primitive parts: box, sphere, cylinder, cone, torus, capsule.	1s	—
`setSkin({ primary, secondary?, pattern?, glow? })`	Your colours. Patterns: solid, stripes, dots, gradient, checker.	1s	—
`setHat({ parts })`	Something on your head, from up to 12 primitive parts.	1s	—
`setAura({ color, intensity? })`	A glow around you.	1s	—
`setTrail({ color, width? })`	A ribbon that follows you.	1s	—
`emitParticles({ preset, at?, color?, count?, spread?, speed?, lifetime? })`	Fire, smoke, sparks, snow, magic, confetti, dust, lightning, bubbles, leaves or stars. Up to 80 at once.	—	—
`playSound(name)`	One of the built-in sounds.	0.2s	—
`showText(word)`	A word over your head, from the built-in list.	1s	—
`emote(name)`	wave, spin, flex, bow, dance or shrug.	1.5s	—

Time, cooldowns and timers

Call	What it does	Cooldown	Power
`after(seconds, fn)`	Run something later. At least 0.25 s, at most 8 pending.	—	—
`every(seconds, fn)`	Run something on repeat. At least 0.25 s apart.	—	—
`cancel(timerId)`	Stop a timer from after() or every().	—	—
`energy()`	Kept for older mods: 100 while this key is ready, 0 while it cools down. Use cooldown() instead.	—	—
`ready(name)`	Whether a call is off cooldown, e.g. ready("self.dash").	—	—
`cooldown()`	Seconds until this key is ready again — 0 when it is.	—	—

Between your own mods

Call	What it does	Cooldown	Power
`emit(eventName, data?)`	Tell your other equipped mods something happened.	—	—
`listen(eventName, fn(data))`	Hear what your other mods emit. Combos live here.	—	—

Extras

Call	What it does	Cooldown	Power
`core.nudge(vector)`	Knock the Core if it is within 10 m. Up to 12 m/s.	2s	10
`core.pull(strength)`	Pull the Core towards you if it is within 14 m. Use in onAbilityHold.	0.15s	14
`mirror(radius)`	Turn enemy projectiles near you around. They become yours.	8s	16
`slowTime({ at?, radius?, factor?, seconds? })`	A bubble where everyone else moves slower, for up to 4 s.	14s	20
`summon("helper-orb" \| "bumper" \| "drone", options?)`	A tiny helper that bumps the nearest enemy for up to 8 s. Up to 2 at once.	10s	18
`blink(direction?, distance?)`	Teleport a short way (up to 8 m) — not over the void.	6s	18

Named values

Projectile looks: fireball, ice, spark, bubble, rock, plasma, leaf, star, arrow, beam. Zone effects: burn, freeze, slow, slippery, lift. Particles: fire, smoke, spark, snow, magic, confetti, dust, lightning, bubbles, leaves, stars. Sounds: whoosh, boom, zap, pop, chime, thud, laser, horn, woosh-up, sparkle, crack, splash. Words: BOOM, ZAP, WHOOSH, POW, YEET, NOPE, GG, OOPS, NICE, BYE, HEY, WOW, MINE, RUN.

A mod cannot

remove a player instantly, or change anybody’s score
touch another player’s mods, code, camera or controls
reach the network, files, the clock or anything outside the match
write free text — words over your head come from a fixed list
change the world for good — every change has a time limit
see what other players cannot see

Examples

Fire Eyes — Shoot fire from your eyes. It pushes people back and leaves them burning.

onRoundStart((me) => {
  setHat({ parts: [
    { shape: 'cone', size: [0.25, 0.35, 0.25], offset: [0, 0.35, 0], color: '#ff6b35', emissive: 1.4 },
    { shape: 'sphere', size: [0.12, 0.12, 0.12], offset: [0, 0.6, 0], color: '#ffd166', emissive: 2 },
  ] });
});

onAbility((me) => {
  for (const side of [-0.12, 0.12]) {
    spawnProjectile({
      from: { x: me.eyes.x + side * Math.cos(Math.atan2(me.look.z, me.look.x) + Math.PI / 2), y: me.eyes.y, z: me.eyes.z + side * Math.sin(Math.atan2(me.look.z, me.look.x) + Math.PI / 2) },
      direction: me.look,
      look: 'fireball',
      color: '#ff7b00',
      speed: 30,
      size: 0.28,
      push: 10,
      effect: 'burn',
    });
  }
  emitParticles({ preset: 'fire', at: 'eyes', color: '#ff9f1c', count: 14, speed: 3, lifetime: 0.4 });
});

Magnet Palms — Hold to pull the Core and everyone nearby towards you.

onRoundStart(() => {
  setWeaponModel({ parts: [
    { shape: 'torus', size: [0.28, 0.28, 0.08], offset: [0.35, 0, -0.2], rotation: [1.57, 0, 0], color: '#e63946', metal: 0.9, rough: 0.2 },
    { shape: 'box', size: [0.1, 0.16, 0.1], offset: [0.35, -0.22, -0.2], color: '#adb5bd', metal: 1 },
  ] });
});

onAbilityHold((me) => {
  const front = { x: me.position.x + me.look.x * 2, y: me.position.y, z: me.position.z + me.look.z * 2 };
  pullTowards(front, 10, 7);
  core.pull(8);
  emitParticles({ preset: 'magic', at: front, color: '#ff4d6d', count: 6, spread: 2, speed: 1, lifetime: 0.4 });
});

Ghost Dash — Dash forward and vanish for two seconds.

onAbility((me) => {
  if (self.dash(me.look, 18)) {
    self.setInvisible(2);
    setTrail({ color: '#c9b8ff', width: 0.5 });
    after(2, () => setTrail({ color: null }));
  }
});

Rocket Jump — Blast yourself into the air, and shove anyone you land near.

let flying = false;
onAbility((me) => {
  if (self.jump(14)) {
    flying = true;
    emitParticles({ preset: 'smoke', at: 'self', color: '#ced4da', count: 30, spread: 0.6, speed: 4, lifetime: 1 });
    playSound('boom');
  }
});
onLand((me, speed) => {
  if (!flying) return;
  flying = false;
  pushFrom(me.position, 12, 4.5);
  showText('POW');
});

Battering Car — Summon a car and drive straight through people. Press F to jump out.

onAbility((me) => {
  if (!me.inVehicle) spawnVehicle('car', { color: '#ffbe0b', seconds: 12 });
});

Sky Train — A train thunders across the arena on the line you are looking along.

onAbility((me) => {
  if (spawnVehicle('train', { color: '#e63946' })) showText('RUN');
});