diff --git a/game/README.md b/game/README.md
index d9e400b..81665f4 100644
--- a/game/README.md
+++ b/game/README.md
@@ -63,3 +63,11 @@ The camera leads movement by up to 120px and eases vertical changes, clamped to
 the complete chunk grid. Rendered camera coordinates stay on whole pixels; layers
 retain the export's scroll factors. Development `?inspect` keeps manual drag panning
 instead of following the hero, for collision review.
+
+Health starts at five cells. Hits grant one second of invulnerability, with a
+white flash and flicker, and roughly 64.5px of knockback. Death plays the supplied
+collapse clip and pixel dust, then restores full health at the last checkpoint.
+Actors register reset callbacks with Player.life; defeated boss ids persist.
+Orange hazards damage and return to safe ground; black no-go resets are free.
+Development F5 tests a normal hit, Shift+F5 a two-cell hit, Ctrl+F5 a hazard reset,
+and Alt+F5 a free no-go reset. These keys are absent from production builds.
diff --git a/game/src/combat/life-visuals.ts b/game/src/combat/life-visuals.ts
new file mode 100644
index 0000000..c448514
--- /dev/null
+++ b/game/src/combat/life-visuals.ts
@@ -0,0 +1,27 @@
+import type Phaser from 'phaser';
+import type { Position } from '../core/events';
+import type { Life } from './life';
+
+export function lifePose(life: Life) {
+  if (life.dead > 0) return { board: 'hero-death', frame: `death-${String(Math.min(11, Math.floor((1 - life.dead) * 12))).padStart(2, '0')}` };
+  if (life.knock > 0) {
+    const time = 1 - life.invulnerable;
+    return { board: 'hero-hurt', frame: time < 0.08 ? 'hit-00'
+      : `knockback-${String(Math.min(2, Math.floor((time - 0.08) * 12))).padStart(2, '0')}` };
+  }
+  return null;
+}
+export function paintLife(sprite: Phaser.GameObjects.Sprite, life: Life, time: number) {
+  if (life.dead === 0 && life.invulnerable > 0.92) sprite.setTintFill(0xffffff);
+  else sprite.clearTint();
+  sprite.setAlpha(life.dead === 0 && life.invulnerable > 0 && Math.floor(time / 80) % 2 ? 0.35 : 1);
+}
+/** Small game particles; no raster assets or changes to the approved art. */
+export function deathDust(scene: Phaser.Scene, position: Position) {
+  for (let i = 0; i < 18; i++) {
+    const pixel = scene.add.rectangle(position.x - 14 + Math.random() * 28,
+      position.y - Math.random() * 76, 2, 2, [0x287c8e, 0x345e83, 0xeadbb4][i % 3]).setDepth(110);
+    scene.tweens.add({ targets: pixel, x: pixel.x - 20 + Math.random() * 40,
+      y: pixel.y - 10 - Math.random() * 20, alpha: 0, duration: 400, onComplete: () => pixel.destroy() });
+  }
+}
diff --git a/game/src/combat/life.test.ts b/game/src/combat/life.test.ts
new file mode 100644
index 0000000..7d061d5
--- /dev/null
+++ b/game/src/combat/life.test.ts
@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest';
+import { Life } from './life';
+describe('health and respawn', () => {
+  it('starts with five cells, rejects hits for one second and charges two for Jenny', () => {
+    const life = new Life({ x: 100, y: 500 });
+    expect(life.health).toBe(5); expect(life.hit(1)).toBe(true); expect(life.health).toBe(4);
+    life.tick(0.99); expect(life.hit(2)).toBe(false);
+    life.tick(0.01); expect(life.hit(2)).toBe(true); expect(life.health).toBe(2);
+  });
+  it('integrates about 1.5m of knockback in either direction', () => {
+    for (const direction of [-1, 1]) {
+      const life = new Life({ x: 100, y: 500 }); life.hit(1, direction);
+      let distance = 0;
+      for (let i = 0; i < 60; i++) distance += life.tick(1 / 120).dx;
+      expect(distance).toBeCloseTo(direction * 64.5, 7);
+    }
+  });
+  it('restores full health at the coffee checkpoint and resets normals but not defeated bosses', () => {
+    const life = new Life({ x: 100, y: 500 }); life.save({ x: 1400, y: 400 });
+    let normal = 0, boss = 0, liveBoss = 0;
+    life.register('rover-1', () => normal++);
+    life.register('jenny', () => boss++, true);
+    life.register('other-boss', () => liveBoss++, true);
+    life.defeatedBosses.add('jenny'); life.hit(5);
+    expect(life.tick(0.9).respawned).toBe(false); expect(life.heal(1)).toBe(false);
+    expect(life.tick(0.1).respawned).toBe(true);
+    expect(life.health).toBe(5); expect(life.safe).toEqual({ x: 1400, y: 400 });
+    expect(normal).toBe(1); expect(boss).toBe(0); expect(liveBoss).toBe(1);
+    life.tick(1); expect(normal).toBe(1); expect(life.defeatedBosses.has('jenny')).toBe(true);
+  });
+  it('keeps no-go resets free and hazard resets at the last safe position', () => {
+    const life = new Life({ x: 100, y: 500 }); life.rememberSafe({ x: 800, y: 300 });
+    expect(life.resetSafe()).toEqual({ x: 800, y: 300 }); expect(life.health).toBe(5);
+    life.hit(1); expect(life.resetSafe()).toEqual({ x: 800, y: 300 }); expect(life.health).toBe(4);
+    expect(life.knock).toBe(0); expect(life.checkpoint).toEqual({ x: 100, y: 500 });
+  });
+  it('caps healing, copies checkpoints and unregisters removed actors', () => {
+    const life = new Life({ x: 100, y: 500 }); life.hit(2); expect(life.heal(1)).toBe(true);
+    expect(life.health).toBe(4); life.heal(10); expect(life.health).toBe(5);
+    const position = { x: 600, y: 350 }; life.save(position); position.x = 0;
+    expect(life.checkpoint.x).toBe(600);
+    let resets = 0; const off = life.register('removed', () => resets++); off();
+    life.tick(1); life.hit(5); life.tick(1); expect(resets).toBe(0);
+  });
+});
diff --git a/game/src/combat/life.ts b/game/src/combat/life.ts
new file mode 100644
index 0000000..a9070a4
--- /dev/null
+++ b/game/src/combat/life.ts
@@ -0,0 +1,62 @@
+import type { Position } from '../core/events';
+export const MAX_HEALTH = 5;
+export const KNOCK_SPEED = 258;
+export const KNOCK_TIME = 0.25;
+interface Actor { boss: boolean; reset: () => void }
+
+/** Per-stage life state. A shared boss set survives scene restarts. */
+export class Life {
+  health = MAX_HEALTH;
+  invulnerable = 0;
+  knock = 0;
+  dead = 0;
+  checkpoint: Position;
+  safe: Position;
+  private direction = 1;
+  private actors = new Map<string, Actor>();
+  constructor(spawn: Position, readonly defeatedBosses = new Set<string>()) {
+    this.checkpoint = { ...spawn }; this.safe = { ...spawn };
+  }
+  hit(damage: number, direction = 1) {
+    if (!Number.isInteger(damage) || damage <= 0) throw new Error('Damage must be a positive integer');
+    if (this.dead > 0 || this.invulnerable > 1e-9) return false;
+    this.health = Math.max(0, this.health - damage);
+    this.invulnerable = 1; this.knock = KNOCK_TIME; this.direction = direction < 0 ? -1 : 1;
+    if (this.health === 0) this.dead = 1;
+    return true;
+  }
+  tick(dt: number) {
+    this.invulnerable = Math.max(0, this.invulnerable - dt);
+    const knocked = Math.min(this.knock, dt);
+    this.knock = Math.max(0, this.knock - dt);
+    if (this.knock < 1e-9) this.knock = 0;
+    const result = { dx: this.dead > 0 ? 0 : this.direction * KNOCK_SPEED * knocked,
+      knockFinished: knocked > 0 && this.knock === 0, respawned: false };
+    if (this.dead > 0) {
+      this.dead = Math.max(0, this.dead - dt);
+      if (this.dead < 1e-9) {
+        this.dead = 0; this.health = MAX_HEALTH; this.invulnerable = 1; this.knock = 0;
+        this.safe = { ...this.checkpoint }; result.respawned = true;
+        for (const [id, actor] of [...this.actors]) if (!actor.boss || !this.defeatedBosses.has(id)) actor.reset();
+      }
+    }
+    return result;
+  }
+  rememberSafe(position: Position) { this.safe = { ...position }; }
+  resetSafe() { this.knock = 0; return { ...this.safe }; }
+  heal(amount: number) {
+    if (!Number.isInteger(amount) || amount <= 0) throw new Error('Healing must be a positive integer');
+    if (this.dead > 0) return false;
+    const next = Math.min(MAX_HEALTH, this.health + amount);
+    const changed = next !== this.health; this.health = next; return changed;
+  }
+  save(position: Position) {
+    if (this.dead > 0) return false;
+    this.checkpoint = { ...position }; this.safe = { ...position }; this.health = MAX_HEALTH;
+    return true;
+  }
+  register(id: string, reset: () => void, boss = false) {
+    const actor = { boss, reset }; this.actors.set(id, actor);
+    return () => { if (this.actors.get(id) === actor) this.actors.delete(id); };
+  }
+}
diff --git a/game/src/core/scaffold.ts b/game/src/core/scaffold.ts
index 40ac39e..68a12d2 100644
--- a/game/src/core/scaffold.ts
+++ b/game/src/core/scaffold.ts
@@ -29,12 +29,17 @@ export class Preload extends Phaser.Scene {
 
 export class Stage extends Phaser.Scene {
   private player?: Player;
+  private defeatedBosses = new Set<string>();
   private follow?: ReturnType<typeof cameraFollow>;
   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.player = new Player(this, data.collisions, data.manifest.region, this.defeatedBosses);
+    this.player.onHealthChanged = health => {
+      const hud = this.scene.get('HUD') as Phaser.Scene & { model?: { setHealth(health: number, at: number): void } };
+      hud.model?.setHealth(health, this.time.now);
+    };
     this.follow = import.meta.env.DEV && new URLSearchParams(location.search).has('inspect')
       ? undefined : cameraFollow(this, data.manifest);
     this.scene.launch('UI');
diff --git a/game/src/player/player.ts b/game/src/player/player.ts
index 9a48ba5..43967fd 100644
--- a/game/src/player/player.ts
+++ b/game/src/player/player.ts
@@ -5,10 +5,15 @@ import { horizontal, move, movement } from './movement';
 import { jump, jumpState, landing } from './jump';
 import { climb, dropThrough, traversal } from './traversal';
 import { catalogue, LocomotionAnimation, type MotionPose } from './animation';
+import { gameEvents } from '../core/events';
+import { Life } from '../combat/life';
+import { deathDust, lifePose, paintLife } from '../combat/life-visuals';
 
 export class Player {
   readonly body: Body;
   readonly sprite: Phaser.GameObjects.Sprite;
+  readonly life: Life;
+  onHealthChanged: (health: number) => void = () => {};
   private motion = movement();
   private keys;
   private debug: Phaser.GameObjects.Graphics;
@@ -19,21 +24,62 @@ export class Player {
   private air;
   private traversal = traversal();
   private animation: LocomotionAnimation;
-  get canAttack() { return this.traversal.ladder === null; }
-  constructor(private scene: Phaser.Scene, private chunks: CollisionChunk[]) {
+  get canAttack() { return this.traversal.ladder === null && this.life.dead === 0 && this.life.knock === 0; }
+  constructor(private scene: Phaser.Scene, private chunks: CollisionChunk[],
+    private region = 'rusty-creek', bosses = new Set<string>()) {
     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.life = new Life(this.body, bosses);
     this.air = jumpState(this.body.y);
     this.animation = new LocomotionAnimation(catalogue(Object.fromEntries(
       ['hero-move', 'hero-run', 'hero-idle', 'hero-air'].map(board => [board, scene.cache.json.get(`${board}.anims`)]))));
     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,W,S,LEFT,RIGHT,UP,DOWN,SPACE,K') 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' })
+    this.label = scene.add.text(20, 135, '', { 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));
+    const offBoss = gameEvents.on('boss-defeated', ({ id }) => this.life.defeatedBosses.add(id));
+    scene.events.once('shutdown', offBoss);
+    if (import.meta.env.DEV) {
+      scene.input.keyboard?.addCapture('F5');
+      const hit = (event: KeyboardEvent) => {
+        if (event.repeat) return;
+        if (event.altKey) this.resetFromDanger();
+        else if (event.ctrlKey) this.resetFromDanger(1);
+        else this.damage(event.shiftKey ? 2 : 1, this.body.x - 10);
+      };
+      scene.input.keyboard?.on('keydown-F5', hit);
+      scene.events.once('shutdown', () => scene.input.keyboard?.off('keydown-F5', hit));
+    }
+  }
+  damage(amount: number, sourceX: number) {
+    if (!this.life.hit(amount, this.body.x >= sourceX ? 1 : -1)) return false;
+    const position = { x: this.body.x, y: this.body.y };
+    gameEvents.emit('player-hit', { health: this.life.health, damage: amount, position });
+    if (this.life.dead > 0) {
+      gameEvents.emit('player-died', { position });
+      this.scene.time.delayedCall(600, () => deathDust(this.scene, position));
+    } else this.body.vy = -90;
+    return true;
+  }
+  heal(amount: number) {
+    if (this.life.heal(amount)) this.onHealthChanged(this.life.health);
+  }
+  saveCheckpoint(id: string) {
+    if (!this.life.save(this.body)) return;
+    this.onHealthChanged(this.life.health);
+    gameEvents.emit('save', { checkpoint: id, region: this.region, position: { x: this.body.x, y: this.body.y } });
+  }
+  private resetPosition(position: { x: number; y: number }) {
+    Object.assign(this.body, position, { vx: 0, vy: 0, grounded: true, sliding: false, slope: 0 });
+    this.motion = movement(); this.air = jumpState(this.body.y); this.traversal = traversal();
+  }
+  private resetFromDanger(damage = 0) {
+    if (damage) this.damage(damage, this.body.x - 10);
+    if (this.life.dead === 0) this.resetPosition(this.life.resetSafe());
   }
   update(milliseconds: number) {
     const pad = this.scene.input.gamepad?.getAll().find(p => p.connected);
@@ -47,11 +93,23 @@ export class Player {
     let remaining = Math.min(milliseconds / 1000, 0.1);
     while (remaining > 1e-9) {
       const dt = Math.min(remaining, 1 / 120);
+      const lifeStep = this.life.tick(dt);
+      if (lifeStep.respawned) {
+        this.resetPosition(this.life.checkpoint);
+        this.onHealthChanged(this.life.health);
+      }
+      if (this.life.dead > 0) { remaining -= dt; continue; }
+      const knocked = lifeStep.dx !== 0;
       const pressed = jumpDown && !this.air.wasDown;
-      const dropped = vertical > 0 && pressed && dropThrough(this.body, this.traversal, geometry);
-      const climbing = climb(this.body, this.traversal, geometry, vertical, axis, pressed, dt);
+      const dropped = !knocked && vertical > 0 && pressed && dropThrough(this.body, this.traversal, geometry);
+      const climbing = !knocked && climb(this.body, this.traversal, geometry, vertical, axis, pressed, dt);
       const wasGrounded = this.body.grounded;
-      if (dropped || climbing) {
+      if (knocked) {
+        this.body.vx = lifeStep.dx / dt;
+        this.traversal = traversal(); this.air.wasDown = jumpDown;
+        this.air.buffer = 0; this.air.coyote = 0; this.air.active = false;
+        this.motion = { ...movement(), facing: this.motion.facing };
+      } else if (dropped || climbing) {
         this.air.wasDown = jumpDown; this.air.buffer = 0; this.air.coyote = 0; this.air.active = false;
         this.motion = movement();
       } else {
@@ -61,28 +119,33 @@ export class Player {
       }
       if (!climbing) stepBody(this.body, geometry, dt, this.traversal.drop > 0);
       landing(this.body, this.air, wasGrounded, dt);
+      if (lifeStep.knockFinished) this.body.vx = 0;
       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, sliding: false, slope: 0 });
-      this.motion = movement();
-      this.air = jumpState(this.body.y);
-      this.traversal = traversal();
+    if (this.life.dead === 0) {
+      const hazard = geometry.flatMap(g => g.hazard).find(box => overlaps(this.body, box));
+      const noGo = this.body.y > 900 || geometry.some(g => g.noGo.some(box => overlaps(this.body, box)));
+      if (hazard) this.resetFromDanger(Number(hazard.damage) || 1);
+      else if (noGo) this.resetFromDanger();
+      else if (this.body.grounded && this.life.knock === 0) this.life.rememberSafe(this.body);
     }
     const desired: MotionPose = this.traversal.ladder ? 'ladder' : this.air.landing > 0
       ? this.air.hard ? 'hard-landing' : 'land' : this.body.sliding ? 'fall'
       : !this.body.grounded ? this.body.vy < 0 ? 'jump' : 'fall'
       : Math.abs(this.body.vx) > 180 ? 'run' : Math.abs(this.body.vx) > 5 ? 'walk' : 'idle';
-    const pose = this.animation.update(desired, desired === 'ladder' && vertical === 0 ? 0 : milliseconds / 1000);
+    const locomotion = this.animation.update(desired, desired === 'ladder' && vertical === 0 ? 0 : milliseconds / 1000);
+    const pose = lifePose(this.life) ?? locomotion;
     if (this.scene.textures.get(pose.board).has(pose.frame)) this.sprite.setTexture(pose.board, pose.frame);
     else this.sprite.setTexture('hero-move', 'idle-00');
     this.sprite.setPosition(Math.round(this.body.x), Math.round(this.body.y)).setFlipX(this.motion.facing < 0);
+    paintLife(this.sprite, this.life, this.scene.time.now);
     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([
+      'hp ' + this.life.health + '/5 | invulnerable ' + this.life.invulnerable.toFixed(2) + 's',
       `vx ${this.body.vx.toFixed(1)} px/s | last ${this.lastSpeed.toFixed(1)} (${(this.lastSpeed / 43).toFixed(2)} m/s)`,
       `held ${this.motion.held.toFixed(2)}s | x ${this.body.x.toFixed(1)} y ${this.body.y.toFixed(1)}`,
       `jump ${this.air.height.toFixed(1)}px | ${this.traversal.ladder ? 'climb' : this.body.sliding ? 'slide' : 'walk'} slope ${(Math.atan(this.body.slope ?? 0) * 180 / Math.PI).toFixed(1)}°`,