diff --git a/game/README.md b/game/README.md
index dc1cd0c..bb9ef12 100644
--- a/game/README.md
+++ b/game/README.md
@@ -26,7 +26,7 @@ JSON-hash atlases with `idle-00` frames and feet pivots `(0.5, 1)`, plus matchin
 `.anims.json` files. Hero: 28×76 body in an 80 px frame; Dexter: 20 px;
 rover: 25 px; crab: 40 px; drone: 45 px; Jenny: 200×70.
 They are development stand-ins for the [production contracts](../docs/13-PRODUCTION-PIPELINE.md),
-and are never copied to `art/`. No gameplay, HUD, or collision is included yet.
+and are never copied to `art/`.
 
 Stage exports from lane A belong at `public/assets/stages/<region>/stage.json`.
 The loader preserves their list order and scroll factors, caches shared plates,
@@ -42,3 +42,9 @@ the same world polylines and boxes that the controller consumes. Collision files
 are fetched next to the exported manifest, validated against the chunk and state,
 then shifted from chunk-local pixels by the manifest's grid coordinates. Original
 metadata is retained; reserved ledges and glide lifts do not become solid surfaces.
+
+Walk with A/D or left/right arrows, or a gamepad stick/D-pad. Holding the same
+direction for 0.4 seconds accelerates from 150.5 to 258 px/s (3.5 to 6 m/s).
+F2 shows speed, hold time, position and the 28×76 player body. The hero currently
+uses the idle atlas pose; animation switching is delivered by #31. Jump, slopes
+and ladders follow in their own issues.
diff --git a/game/src/core/scaffold.ts b/game/src/core/scaffold.ts
index 80f26ca..1292e06 100644
--- a/game/src/core/scaffold.ts
+++ b/game/src/core/scaffold.ts
@@ -4,6 +4,7 @@ import { drawStage } from '../stage/render';
 import type { StageManifest, RegionState } from '../stage/manifest';
 import { loadCollisions, type CollisionChunk } from '../stage/collision';
 import { collisionDebug } from '../stage/collision-debug';
+import { Player } from '../player/player';
 
 // Bootstrap-only scenes live in lane B until lane A provides story/UI scenes.
 export class Boot extends Phaser.Scene {
@@ -26,10 +27,12 @@ export class Preload extends Phaser.Scene {
 }
 
 export class Stage extends Phaser.Scene {
+  private player?: Player;
   constructor() { super('Stage'); }
   create(data: { manifest: StageManifest; state: RegionState; collisions: CollisionChunk[] }) {
     drawStage(this, data.manifest, data.state);
     collisionDebug(this, data.collisions);
+    this.player = new Player(this, data.collisions);
     this.scene.launch('UI');
     // Development inspection only; camera follow is implemented separately in #32.
     if (import.meta.env.DEV && new URLSearchParams(location.search).has('inspect')) {
@@ -41,6 +44,7 @@ export class Stage extends Phaser.Scene {
       });
     }
   }
+  update(_time: number, delta: number) { this.player?.update(delta); }
 }
 
 export class UI extends Phaser.Scene {
diff --git a/game/src/player/body.ts b/game/src/player/body.ts
new file mode 100644
index 0000000..4b03a29
--- /dev/null
+++ b/game/src/player/body.ts
@@ -0,0 +1,43 @@
+import type { Box, Geometry } from '../stage/collision';
+export const BODY_WIDTH = 28;
+export const BODY_HEIGHT = 76;
+export interface Body { x: number; y: number; vx: number; vy: number; grounded: boolean }
+export function overlaps(body: Body, box: Box) {
+  return body.x + 14 > box.x && body.x - 14 < box.x + box.w
+    && body.y > box.y && body.y - BODY_HEIGHT < box.y + box.h;
+}
+
+/** Feet origin, swept wall/floor checks. Slope and one-way policies follow separately. */
+export function stepBody(body: Body, geometry: Geometry[], dt: number) {
+  const oldX = body.x, oldY = body.y;
+  body.x += body.vx * dt;
+  for (const world of geometry) for (const wall of world.solid) {
+    if (oldY <= wall.y || oldY - BODY_HEIGHT >= wall.y + wall.h) continue;
+    if (body.vx > 0 && oldX + 14 <= wall.x && body.x + 14 > wall.x) {
+      body.x = wall.x - 14; body.vx = 0;
+    } else if (body.vx < 0 && oldX - 14 >= wall.x + wall.w && body.x - 14 < wall.x + wall.w) {
+      body.x = wall.x + wall.w + 14; body.vx = 0;
+    }
+  }
+  body.vy = Math.min(900, body.vy + 1200 * dt);
+  let nextY = body.y + body.vy * dt;
+  body.grounded = false;
+  for (const world of geometry) {
+    for (const line of world.walk) for (let i = 1; i < line.length; i++) {
+      const [a, b] = [line[i - 1], line[i]];
+      if (a[1] !== b[1] || body.x < a[0] || body.x > b[0]) continue;
+      if (body.vy >= 0 && oldY <= a[1] + 0.01 && nextY >= a[1]) {
+        nextY = a[1]; body.vy = 0; body.grounded = true;
+      }
+    }
+    for (const wall of world.solid) {
+      if (body.x + 14 <= wall.x || body.x - 14 >= wall.x + wall.w) continue;
+      if (body.vy >= 0 && oldY <= wall.y && nextY >= wall.y) {
+        nextY = wall.y; body.vy = 0; body.grounded = true;
+      } else if (body.vy < 0 && oldY - BODY_HEIGHT >= wall.y + wall.h && nextY - BODY_HEIGHT < wall.y + wall.h) {
+        nextY = wall.y + wall.h + BODY_HEIGHT; body.vy = 0;
+      }
+    }
+  }
+  body.y = nextY;
+}
diff --git a/game/src/player/movement.test.ts b/game/src/player/movement.test.ts
new file mode 100644
index 0000000..0cd6459
--- /dev/null
+++ b/game/src/player/movement.test.ts
@@ -0,0 +1,56 @@
+import { describe, expect, it } from 'vitest';
+import { horizontal, move, movement, RUN_SPEED, WALK_SPEED } from './movement';
+import { stepBody, type Body } from './body';
+import type { Geometry } from '../stage/collision';
+
+describe('walk/run controls', () => {
+  it('reaches walking speed before 0.4s and then running speed', () => {
+    const state = movement();
+    for (let i = 0; i < 20; i++) move(state, 1, 1 / 60);
+    expect(state.vx).toBe(WALK_SPEED);
+    for (let i = 0; i < 10; i++) move(state, 1, 1 / 60);
+    expect(state.vx).toBe(RUN_SPEED);
+  });
+  it('decelerates to rest and resets run timing on release or reversal', () => {
+    const state = movement();
+    for (let i = 0; i < 60; i++) move(state, 1, 1 / 60);
+    move(state, 0, 1 / 60);
+    expect(state.vx).toBeGreaterThan(0); expect(state.vx).toBeLessThan(RUN_SPEED);
+    for (let i = 0; i < 10; i++) move(state, 0, 1 / 60);
+    expect(state.vx).toBe(0); expect(state.held).toBe(0);
+    move(state, -1, 1 / 60);
+    expect(state.facing).toBe(-1); expect(state.held).toBeCloseTo(1 / 60);
+    move(state, 1, 1 / 60); expect(state.held).toBeCloseTo(1 / 60);
+  });
+  it('handles keyboard opposites, stick dead zone and D-pad priority', () => {
+    expect(horizontal(true, false)).toBe(-1); expect(horizontal(false, true)).toBe(1);
+    expect(horizontal(true, true, 1)).toBe(0); expect(horizontal(false, false, 0.19)).toBe(0);
+    expect(horizontal(false, false, -1)).toBe(-1); expect(horizontal(false, false, 0.6)).toBeCloseTo(0.5);
+    expect(horizontal(false, false, 1, true)).toBe(-1);
+  });
+  it('is consistent across rendered frame rates', () => {
+    const run = (fps: number) => {
+      const state = movement(); let x = 0;
+      for (let i = 0; i < fps; i++) { move(state, 1, 1 / fps); x += state.vx / fps; }
+      return x;
+    };
+    expect(Math.abs(run(60) - run(120))).toBeLessThan(3);
+  });
+});
+
+describe('body foundation', () => {
+  const world: Geometry = { walk: [[[0, 500], [1000, 500]]], slide: [], oneWay: [], solid: [],
+    climb: [], noGo: [], hazard: [], interact: [], spawn: [], ledge: [], glideLift: [] };
+  it('keeps feet on the authored floor and catches a fall', () => {
+    const body: Body = { x: 100, y: 450, vx: 150, vy: 0, grounded: false };
+    for (let i = 0; i < 60; i++) stepBody(body, [world], 1 / 120);
+    expect(body.y).toBe(500); expect(body.grounded).toBe(true); expect(body.x).toBeCloseTo(175);
+  });
+  it('stops the 28px body at a swept wall and lands on box tops', () => {
+    const geometry = { ...world, solid: [{ x: 200, y: 300, w: 20, h: 200 }] };
+    const body: Body = { x: 180, y: 500, vx: 258, vy: 0, grounded: true };
+    stepBody(body, [geometry], 0.1); expect(body.x).toBe(186); expect(body.vx).toBe(0);
+    Object.assign(body, { x: 210, y: 290, vx: 0, vy: 100 });
+    stepBody(body, [geometry], 0.1); expect(body.y).toBe(300); expect(body.grounded).toBe(true);
+  });
+});
diff --git a/game/src/player/movement.ts b/game/src/player/movement.ts
new file mode 100644
index 0000000..1796607
--- /dev/null
+++ b/game/src/player/movement.ts
@@ -0,0 +1,25 @@
+export const WALK_SPEED = 3.5 * 43;
+export const RUN_SPEED = 6 * 43;
+export const RUN_DELAY = 0.4;
+export interface Movement { vx: number; held: number; direction: number; facing: -1 | 1 }
+export const movement = (): Movement => ({ vx: 0, held: 0, direction: 0, facing: 1 });
+export const approach = (value: number, target: number, amount: number) =>
+  value + Math.sign(target - value) * Math.min(Math.abs(target - value), amount);
+
+/** Dead zone prevents stick drift from starting the run timer. D-pad is digital. */
+export function horizontal(left: boolean, right: boolean, stick = 0, padLeft = false, padRight = false) {
+  const keys = Number(right) - Number(left);
+  const pad = Number(padRight) - Number(padLeft);
+  if (left || right) return keys;
+  if (padLeft || padRight) return pad;
+  return Math.abs(stick) <= 0.2 ? 0 : Math.sign(stick) * Math.min(1, (Math.abs(stick) - 0.2) / 0.8);
+}
+
+export function move(state: Movement, axis: number, dt: number) {
+  const direction = Math.sign(axis);
+  state.held = direction === 0 ? 0 : direction === state.direction ? state.held + dt : dt;
+  state.direction = direction;
+  if (direction) state.facing = direction as -1 | 1;
+  const speed = state.held + 1e-9 >= RUN_DELAY ? RUN_SPEED : WALK_SPEED;
+  state.vx = approach(state.vx, axis * speed, (direction ? 1500 : 2000) * dt);
+}
diff --git a/game/src/player/player.ts b/game/src/player/player.ts
new file mode 100644
index 0000000..3f560f6
--- /dev/null
+++ b/game/src/player/player.ts
@@ -0,0 +1,52 @@
+import Phaser from 'phaser';
+import type { CollisionChunk } from '../stage/collision';
+import { BODY_HEIGHT, BODY_WIDTH, overlaps, stepBody, type Body } from './body';
+import { horizontal, move, movement } from './movement';
+
+export class Player {
+  readonly body: Body;
+  readonly sprite: Phaser.GameObjects.Sprite;
+  private motion = movement();
+  private keys;
+  private debug: Phaser.GameObjects.Graphics;
+  private label: Phaser.GameObjects.Text;
+  private showDebug = false;
+  private lastSpeed = 0;
+  private spawn;
+  constructor(private scene: Phaser.Scene, private chunks: CollisionChunk[]) {
+    this.spawn = chunks.flatMap(c => c.world.spawn).find(p => p.kind === 'player') ?? { x: 120, y: 461 };
+    this.body = { x: this.spawn.x, y: this.spawn.y, vx: 0, vy: 0, grounded: true };
+    this.sprite = scene.add.sprite(this.body.x, this.body.y, 'hero-move', 'idle-00').setOrigin(0.5, 1).setDepth(100);
+    this.keys = scene.input.keyboard!.addKeys('A,D,LEFT,RIGHT') as Record<string, Phaser.Input.Keyboard.Key>;
+    this.debug = scene.add.graphics().setDepth(10001);
+    this.label = scene.add.text(20, 80, '', { fontFamily: 'monospace', fontSize: '18px', backgroundColor: '#17242d' })
+      .setScrollFactor(0).setDepth(10002).setVisible(false);
+    const toggle = () => { this.showDebug = !this.showDebug; this.label.setVisible(this.showDebug); };
+    scene.input.keyboard?.on('keydown-F2', toggle);
+    scene.events.once('shutdown', () => scene.input.keyboard?.off('keydown-F2', toggle));
+  }
+  update(milliseconds: number) {
+    const pad = this.scene.input.gamepad?.getAll().find(p => p.connected);
+    const axis = horizontal(this.keys.A.isDown || this.keys.LEFT.isDown, this.keys.D.isDown || this.keys.RIGHT.isDown,
+      pad?.leftStick.x, pad?.left, pad?.right);
+    // Substeps keep wall and floor contacts stable during slow rendered frames.
+    let remaining = Math.min(milliseconds / 1000, 0.1);
+    while (remaining > 1e-9) {
+      const dt = Math.min(remaining, 1 / 120);
+      move(this.motion, axis, dt); this.body.vx = this.motion.vx;
+      stepBody(this.body, this.chunks.map(c => c.world), dt);
+      this.motion.vx = this.body.vx;
+      remaining -= dt;
+    }
+    if (this.body.y > 900 || this.chunks.some(c => c.world.noGo.some(box => overlaps(this.body, box)))) {
+      Object.assign(this.body, { x: this.spawn.x, y: this.spawn.y, vx: 0, vy: 0, grounded: true });
+      this.motion = movement();
+    }
+    this.sprite.setPosition(Math.round(this.body.x), Math.round(this.body.y)).setFlipX(this.motion.facing < 0);
+    if (axis) this.lastSpeed = Math.abs(this.body.vx);
+    this.debug.clear();
+    if (this.showDebug) this.debug.lineStyle(2, 0xffffff).strokeRect(this.body.x - BODY_WIDTH / 2,
+      this.body.y - BODY_HEIGHT, BODY_WIDTH, BODY_HEIGHT);
+    this.label.setText(`vx ${this.body.vx.toFixed(1)} px/s | last ${this.lastSpeed.toFixed(1)} (${(this.lastSpeed / 43).toFixed(2)} m/s)\nheld ${this.motion.held.toFixed(2)}s | x ${this.body.x.toFixed(1)} y ${this.body.y.toFixed(1)}`);
+  }
+}