diff --git a/app.js b/app.js
index 60689a0..551008c 100644
--- a/app.js
+++ b/app.js
@@ -34,6 +34,26 @@ let debugOverlay;
 let frameCount = 0, lastFPSTime = 0, fps = 0;
 let chatOpen = true;
 let loadProgress = 0;
+let performanceTier = 'high'; // 'high' | 'medium' | 'low'
+
+// ═══ NAVIGATION SYSTEM ═══
+const NAV_MODES = ['walk', 'orbit', 'fly'];
+let navModeIdx = 0; // default: walk
+
+// Orbit state
+const orbitState = {
+  target:  new THREE.Vector3(0, 2, 0),
+  radius:  14,
+  theta:   Math.PI,       // azimuthal (horizontal rotation)
+  phi:     Math.PI / 6,   // polar (vertical tilt, 0=top)
+  minR:    3,
+  maxR:    40,
+  lastX:   0,
+  lastY:   0,
+};
+
+// Fly state — separate Y so walk and fly share XZ history
+let flyY = 2;
 
 // ═══ INIT ═══
 function init() {
@@ -45,11 +65,13 @@ function init() {
   const canvas = document.getElementById('nexus-canvas');
   renderer = new THREE.WebGLRenderer({ canvas, antialias: true });
   renderer.setSize(window.innerWidth, window.innerHeight);
-  renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
   renderer.toneMapping = THREE.ACESFilmicToneMapping;
   renderer.toneMappingExposure = 1.2;
   renderer.shadowMap.enabled = true;
   renderer.shadowMap.type = THREE.PCFSoftShadowMap;
+
+  // Performance budget — must run before scene objects are created
+  performanceTier = detectPerformanceTier();
   updateLoad(20);
 
   // Scene
@@ -125,6 +147,33 @@ function updateLoad(pct) {
   if (fill) fill.style.width = pct + '%';
 }
 
+// ═══ PERFORMANCE BUDGET ═══
+function detectPerformanceTier() {
+  const isMobile = /Mobi|Android|iPhone|iPad/i.test(navigator.userAgent) || window.innerWidth < 768;
+  const cores = navigator.hardwareConcurrency || 4;
+
+  if (isMobile) {
+    renderer.setPixelRatio(1);
+    renderer.shadowMap.enabled = false;
+    renderer.toneMappingExposure = 1.0;
+    return 'low';
+  } else if (cores < 8) {
+    renderer.setPixelRatio(Math.min(window.devicePixelRatio, 1.5));
+    renderer.shadowMap.type = THREE.BasicShadowMap;
+    return 'medium';
+  } else {
+    // M3 Max / high-end desktop — full quality
+    renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
+    return 'high';
+  }
+}
+
+function particleCount(base) {
+  if (performanceTier === 'low')   return Math.floor(base * 0.25);
+  if (performanceTier === 'medium') return Math.floor(base * 0.6);
+  return base;
+}
+
 // ═══ SKYBOX ═══
 function createSkybox() {
   // Procedural nebula skybox using shader
@@ -230,8 +279,9 @@ function createLighting() {
   // Main directional (moonlight feel)
   const dirLight = new THREE.DirectionalLight(0x4466aa, 0.6);
   dirLight.position.set(10, 20, 10);
-  dirLight.castShadow = true;
-  dirLight.shadow.mapSize.set(1024, 1024);
+  dirLight.castShadow = renderer.shadowMap.enabled;
+  const shadowRes = performanceTier === 'high' ? 2048 : performanceTier === 'medium' ? 1024 : 512;
+  dirLight.shadow.mapSize.set(shadowRes, shadowRes);
   dirLight.shadow.camera.near = 0.5;
   dirLight.shadow.camera.far = 80;
   dirLight.shadow.camera.left = -30;
@@ -617,7 +667,7 @@ function createPortal() {
 
 // ═══ PARTICLES ═══
 function createParticles() {
-  const count = 1500;
+  const count = particleCount(1500);
   const geo = new THREE.BufferGeometry();
   const positions = new Float32Array(count * 3);
   const colors = new Float32Array(count * 3);
@@ -681,7 +731,7 @@ function createParticles() {
 }
 
 function createDustParticles() {
-  const count = 500;
+  const count = particleCount(500);
   const geo = new THREE.BufferGeometry();
   const positions = new Float32Array(count * 3);
 
@@ -787,6 +837,33 @@ function createAmbientStructures() {
   scene.add(pedestal);
 }
 
+// ═══ NAVIGATION MODE ═══
+function cycleNavMode() {
+  navModeIdx = (navModeIdx + 1) % NAV_MODES.length;
+  const mode = NAV_MODES[navModeIdx];
+
+  // Sync orbit target/radius from current camera when switching into orbit
+  if (mode === 'orbit') {
+    const dir = new THREE.Vector3(0, 0, -1).applyEuler(playerRot);
+    orbitState.target.copy(playerPos).addScaledVector(dir, orbitState.radius);
+    orbitState.target.y = Math.max(0, orbitState.target.y);
+    // Recompute angles from current camera → target vector
+    const toCamera = new THREE.Vector3().subVectors(playerPos, orbitState.target);
+    orbitState.radius = toCamera.length();
+    orbitState.theta = Math.atan2(toCamera.x, toCamera.z);
+    orbitState.phi = Math.acos(Math.max(-1, Math.min(1, toCamera.y / orbitState.radius)));
+  }
+  // Sync fly Y from current walk position
+  if (mode === 'fly') flyY = playerPos.y;
+
+  updateNavModeUI(mode);
+}
+
+function updateNavModeUI(mode) {
+  const el = document.getElementById('nav-mode-label');
+  if (el) el.textContent = mode.toUpperCase();
+}
+
 // ═══ CONTROLS ═══
 function setupControls() {
   document.addEventListener('keydown', (e) => {
@@ -803,25 +880,51 @@ function setupControls() {
     if (e.key === 'Escape') {
       document.getElementById('chat-input').blur();
     }
+    // V cycles navigation modes
+    if (e.key.toLowerCase() === 'v' && document.activeElement !== document.getElementById('chat-input')) {
+      cycleNavMode();
+    }
   });
   document.addEventListener('keyup', (e) => {
     keys[e.key.toLowerCase()] = false;
   });
 
-  // Mouse look
+  // Mouse look / orbit drag
   const canvas = document.getElementById('nexus-canvas');
   canvas.addEventListener('mousedown', (e) => {
-    if (e.target === canvas) mouseDown = true;
+    if (e.target === canvas) {
+      mouseDown = true;
+      orbitState.lastX = e.clientX;
+      orbitState.lastY = e.clientY;
+    }
   });
   document.addEventListener('mouseup', () => { mouseDown = false; });
   document.addEventListener('mousemove', (e) => {
     if (!mouseDown) return;
     if (document.activeElement === document.getElementById('chat-input')) return;
-    playerRot.y -= e.movementX * 0.003;
-    playerRot.x -= e.movementY * 0.003;
-    playerRot.x = Math.max(-Math.PI / 3, Math.min(Math.PI / 3, playerRot.x));
+    const mode = NAV_MODES[navModeIdx];
+    if (mode === 'orbit') {
+      const dx = e.clientX - orbitState.lastX;
+      const dy = e.clientY - orbitState.lastY;
+      orbitState.lastX = e.clientX;
+      orbitState.lastY = e.clientY;
+      orbitState.theta -= dx * 0.005;
+      orbitState.phi   = Math.max(0.05, Math.min(Math.PI * 0.85, orbitState.phi + dy * 0.005));
+    } else {
+      // Walk and Fly: mouse look
+      playerRot.y -= e.movementX * 0.003;
+      playerRot.x -= e.movementY * 0.003;
+      playerRot.x = Math.max(-Math.PI / 3, Math.min(Math.PI / 3, playerRot.x));
+    }
   });
 
+  // Scroll to zoom in orbit mode
+  canvas.addEventListener('wheel', (e) => {
+    if (NAV_MODES[navModeIdx] === 'orbit') {
+      orbitState.radius = Math.max(orbitState.minR, Math.min(orbitState.maxR, orbitState.radius + e.deltaY * 0.02));
+    }
+  }, { passive: true });
+
   // Chat toggle
   document.getElementById('chat-toggle').addEventListener('click', () => {
     chatOpen = !chatOpen;
@@ -878,30 +981,77 @@ function gameLoop() {
   const delta = Math.min(clock.getDelta(), 0.1);
   const elapsed = clock.elapsedTime;
 
-  // Movement
-  if (document.activeElement !== document.getElementById('chat-input')) {
-    const speed = 6 * delta;
-    const dir = new THREE.Vector3();
-    if (keys['w']) dir.z -= 1;
-    if (keys['s']) dir.z += 1;
-    if (keys['a']) dir.x -= 1;
-    if (keys['d']) dir.x += 1;
-    if (dir.length() > 0) {
-      dir.normalize().multiplyScalar(speed);
-      dir.applyAxisAngle(new THREE.Vector3(0, 1, 0), playerRot.y);
-      playerPos.add(dir);
-      // Clamp to platform
-      const maxR = 24;
-      const dist = Math.sqrt(playerPos.x * playerPos.x + playerPos.z * playerPos.z);
-      if (dist > maxR) {
-        playerPos.x *= maxR / dist;
-        playerPos.z *= maxR / dist;
+  // ─── Navigation update ───────────────────────────────────────────
+  const mode = NAV_MODES[navModeIdx];
+  const chatActive = document.activeElement === document.getElementById('chat-input');
+
+  if (mode === 'walk') {
+    if (!chatActive) {
+      const speed = 6 * delta;
+      const dir = new THREE.Vector3();
+      if (keys['w']) dir.z -= 1;
+      if (keys['s']) dir.z += 1;
+      if (keys['a']) dir.x -= 1;
+      if (keys['d']) dir.x += 1;
+      if (dir.length() > 0) {
+        dir.normalize().multiplyScalar(speed);
+        dir.applyAxisAngle(new THREE.Vector3(0, 1, 0), playerRot.y);
+        playerPos.add(dir);
+        // Clamp to platform
+        const maxR = 24;
+        const dist = Math.sqrt(playerPos.x * playerPos.x + playerPos.z * playerPos.z);
+        if (dist > maxR) { playerPos.x *= maxR / dist; playerPos.z *= maxR / dist; }
       }
     }
-  }
+    playerPos.y = 2; // fixed eye height in walk mode
+    camera.position.copy(playerPos);
+    camera.rotation.set(playerRot.x, playerRot.y, 0, 'YXZ');
 
-  camera.position.copy(playerPos);
-  camera.rotation.set(playerRot.x, playerRot.y, 0, 'YXZ');
+  } else if (mode === 'orbit') {
+    // Pan target with WASD
+    if (!chatActive) {
+      const speed = 8 * delta;
+      const pan = new THREE.Vector3();
+      if (keys['w']) pan.z -= 1;
+      if (keys['s']) pan.z += 1;
+      if (keys['a']) pan.x -= 1;
+      if (keys['d']) pan.x += 1;
+      if (pan.length() > 0) {
+        pan.normalize().multiplyScalar(speed);
+        pan.applyAxisAngle(new THREE.Vector3(0, 1, 0), orbitState.theta);
+        orbitState.target.add(pan);
+        orbitState.target.y = Math.max(0, Math.min(20, orbitState.target.y));
+      }
+    }
+    // Position camera on sphere around target
+    const r = orbitState.radius;
+    camera.position.set(
+      orbitState.target.x + r * Math.sin(orbitState.phi) * Math.sin(orbitState.theta),
+      orbitState.target.y + r * Math.cos(orbitState.phi),
+      orbitState.target.z + r * Math.sin(orbitState.phi) * Math.cos(orbitState.theta)
+    );
+    camera.lookAt(orbitState.target);
+    // Keep playerPos in sync so switching back to walk is smooth
+    playerPos.copy(camera.position);
+    playerRot.y = orbitState.theta;
+
+  } else if (mode === 'fly') {
+    if (!chatActive) {
+      const speed = 8 * delta;
+      const forward = new THREE.Vector3(-Math.sin(playerRot.y), 0, -Math.cos(playerRot.y));
+      const right   = new THREE.Vector3( Math.cos(playerRot.y), 0, -Math.sin(playerRot.y));
+      if (keys['w'])     playerPos.addScaledVector(forward, speed);
+      if (keys['s'])     playerPos.addScaledVector(forward, -speed);
+      if (keys['a'])     playerPos.addScaledVector(right, -speed);
+      if (keys['d'])     playerPos.addScaledVector(right,  speed);
+      if (keys['q'] || keys[' '])     flyY += speed;
+      if (keys['e'] || keys['shift']) flyY -= speed;
+      flyY = Math.max(0.5, Math.min(30, flyY));
+      playerPos.y = flyY;
+    }
+    camera.position.copy(playerPos);
+    camera.rotation.set(playerRot.x, playerRot.y, 0, 'YXZ');
+  }
 
   // Animate skybox
   const sky = scene.getObjectByName('skybox');
@@ -964,8 +1114,8 @@ function gameLoop() {
   if (debugOverlay) {
     const info = renderer.info;
     debugOverlay.textContent =
-      `FPS: ${fps}  Draw: ${info.render?.calls}  Tri: ${info.render?.triangles}\n` +
-      `Pos: ${playerPos.x.toFixed(1)}, ${playerPos.y.toFixed(1)}, ${playerPos.z.toFixed(1)}`;
+      `FPS: ${fps}  Draw: ${info.render?.calls}  Tri: ${info.render?.triangles}  [${performanceTier}]\n` +
+      `Pos: ${playerPos.x.toFixed(1)}, ${playerPos.y.toFixed(1)}, ${playerPos.z.toFixed(1)}  NAV: ${NAV_MODES[navModeIdx]}`;
   }
   renderer.info.reset();
 }
diff --git a/index.html b/index.html
index 3a2c6ea..48dd6ab 100644
--- a/index.html
+++ b/index.html
@@ -95,9 +95,11 @@
     </div>
   </div>
 
-  <!-- Minimap / Controls hint -->
+  <!-- Controls hint + nav mode -->
   <div class="hud-controls">
-    <span>WASD</span> move &nbsp; <span>Mouse</span> look &nbsp; <span>Enter</span> chat
+    <span>WASD</span> move &nbsp; <span>Mouse</span> look &nbsp; <span>Enter</span> chat &nbsp;
+    <span>V</span> mode: <span id="nav-mode-label">WALK</span>
+    <span id="nav-mode-hint" class="nav-mode-hint"></span>
   </div>
 </div>
 
diff --git a/style.css b/style.css
index 519b05e..1b5f3a1 100644
--- a/style.css
+++ b/style.css
@@ -215,6 +215,11 @@ canvas#nexus-canvas {
   color: var(--color-primary);
   font-weight: 600;
 }
+#nav-mode-label {
+  color: var(--color-gold);
+  font-weight: 700;
+  letter-spacing: 0.05em;
+}
 
 /* === CHAT PANEL === */
 .chat-panel {