diff --git a/src/js/net/minecraft/client/GameWindow.js b/src/js/net/minecraft/client/GameWindow.js
index 80b3c87..1af33a3 100644
--- a/src/js/net/minecraft/client/GameWindow.js
+++ b/src/js/net/minecraft/client/GameWindow.js
@@ -28,8 +28,23 @@ window.GameWindow = class {
         // Mouse motion
         document.addEventListener('mousemove', event => this.onMouseMove(event), false);
 
+        // Losing focus event
+        window.addEventListener("mouseout", function () {
+            if (minecraft.currentScreen === null) {
+                minecraft.displayScreen(new GuiIngameMenu());
+            }
+        });
+
         // Mouse buttons
-        document.addEventListener('click', event => minecraft.onMouseClicked(event.button), false);
+        document.addEventListener('click', function (event) {
+            // Handle in-game mouse click
+            minecraft.onMouseClicked(event.button);
+
+            // Handle mouse click on screen
+            if (!(minecraft.currentScreen === null)) {
+                minecraft.currentScreen.mouseClicked(event.x, event.y, event.code);
+            }
+        }, false);
 
         // Keyboard interaction with screen
         window.addEventListener('keydown', function (event) {
@@ -41,6 +56,9 @@ window.GameWindow = class {
                     // Cancel browser interaction
                     event.preventDefault();
                 }
+            } else if (event.code === 'Escape') {
+                event.preventDefault();
+                minecraft.displayScreen(new GuiIngameMenu());
             }
         });
 
@@ -49,7 +67,12 @@ window.GameWindow = class {
     }
 
     requestFocus() {
-        this.renderer.canvasElement.requestPointerLock();
+        let scope = this;
+
+        setTimeout(function () {
+            window.focus();
+            scope.renderer.canvasElement.requestPointerLock();
+        }, 0);
     }
 
     loadRenderer(renderer) {
@@ -64,10 +87,10 @@ window.GameWindow = class {
         this.onResize();
 
         // Request focus
-        let minecraft = this.minecraft;
+        let scope = this;
         canvas.onclick = function () {
-            if (minecraft.currentScreen === null) {
-                canvas.requestPointerLock();
+            if (scope.minecraft.currentScreen === null) {
+                scope.requestFocus();
             }
         }
     }
@@ -90,14 +113,13 @@ window.GameWindow = class {
 
         // Reinitialize current screen
         if (!(this.minecraft.currentScreen === null)) {
-            this.minecraft.currentScreen.init(this.minecraft, this.width, this.height);
+            this.minecraft.currentScreen.setup(this.minecraft, this.width, this.height);
         }
     }
 
     onFocusChanged() {
         this.mouseLocked = document.pointerLockElement === this.renderer.canvasElement;
 
-        // Open in-game menu
         if (!this.mouseLocked && this.minecraft.currentScreen === null) {
             this.minecraft.displayScreen(new GuiIngameMenu());
         }
diff --git a/src/js/net/minecraft/client/Minecraft.js b/src/js/net/minecraft/client/Minecraft.js
index 8ec1ec5..d5550bc 100644
--- a/src/js/net/minecraft/client/Minecraft.js
+++ b/src/js/net/minecraft/client/Minecraft.js
@@ -31,7 +31,7 @@ window.Minecraft = class {
         this.worldRenderer.scene.add(this.world.group);
 
         // Create player
-        this.player = new Player(this.world);
+        this.player = new Player(this, this.world);
         this.pickedBlock = 1;
 
         // Initialize
@@ -48,6 +48,10 @@ window.Minecraft = class {
         this.requestNextFrame();
     }
 
+    hasInGameFocus() {
+        return this.window.mouseLocked && this.currentScreen === null;
+    }
+
     requestNextFrame() {
         let scope = this;
         requestAnimationFrame(function () {
@@ -88,7 +92,7 @@ window.Minecraft = class {
 
     onRender(partialTicks) {
         // Player rotation
-        if (this.window.mouseLocked && !(this.currentScreen === "null")) {
+        if (this.hasInGameFocus()) {
             this.player.turn(this.window.mouseMotionX, this.window.mouseMotionY);
 
             this.window.mouseMotionX = 0;
@@ -112,7 +116,7 @@ window.Minecraft = class {
         if (screen === null) {
             this.window.requestFocus();
         } else {
-            screen.init(this, this.window.width, this.window.height);
+            screen.setup(this, this.window.width, this.window.height);
         }
     }
 
diff --git a/src/js/net/minecraft/client/entity/Player.js b/src/js/net/minecraft/client/entity/Player.js
index f397385..21c7b3d 100644
--- a/src/js/net/minecraft/client/entity/Player.js
+++ b/src/js/net/minecraft/client/entity/Player.js
@@ -1,6 +1,7 @@
 window.Player = class {
 
-    constructor(world) {
+    constructor(minecraft, world) {
+        this.minecraft = minecraft;
         this.world = world;
 
         this.prevX = 0;
@@ -309,38 +310,40 @@ window.Player = class {
         let jumping = false;
         let sneaking = false;
 
-        if (Keyboard.isKeyDown("KeyR")) { // R
-            this.respawn();
-        }
-        if (Keyboard.isKeyDown("KeyW")) { // W
-            moveForward++;
-        }
-        if (Keyboard.isKeyDown("KeyS")) { // S
-            moveForward--;
-        }
-        if (Keyboard.isKeyDown("KeyA")) { // A
-            moveStrafe++;
-        }
-        if (Keyboard.isKeyDown("KeyD")) { // D
-            moveStrafe--;
-        }
-        if (Keyboard.isKeyDown("Space")) { // Space
-            jumping = true;
-        }
-        if (Keyboard.isKeyDown("ShiftLeft")) { // Shift
-            if (this.moveForward > 0 && !this.sneaking && !this.sprinting && this.motionX !== 0 && this.motionZ !== 0) {
-                this.sprinting = true;
-
-                this.updateFOVModifier();
+        if (this.minecraft.hasInGameFocus()) {
+            if (Keyboard.isKeyDown("KeyR")) { // R
+                this.respawn();
             }
-        }
-        if (Keyboard.isKeyDown("KeyQ")) { // Q
-            sneaking = true;
-        }
+            if (Keyboard.isKeyDown("KeyW")) { // W
+                moveForward++;
+            }
+            if (Keyboard.isKeyDown("KeyS")) { // S
+                moveForward--;
+            }
+            if (Keyboard.isKeyDown("KeyA")) { // A
+                moveStrafe++;
+            }
+            if (Keyboard.isKeyDown("KeyD")) { // D
+                moveStrafe--;
+            }
+            if (Keyboard.isKeyDown("Space")) { // Space
+                jumping = true;
+            }
+            if (Keyboard.isKeyDown("ShiftLeft")) { // Shift
+                if (this.moveForward > 0 && !this.sneaking && !this.sprinting && this.motionX !== 0 && this.motionZ !== 0) {
+                    this.sprinting = true;
 
-        if (sneaking) {
-            moveStrafe = moveStrafe * 0.3;
-            moveForward = moveForward * 0.3;
+                    this.updateFOVModifier();
+                }
+            }
+            if (Keyboard.isKeyDown("KeyQ")) { // Q
+                sneaking = true;
+            }
+
+            if (sneaking) {
+                moveStrafe = moveStrafe * 0.3;
+                moveForward = moveForward * 0.3;
+            }
         }
 
         this.moveForward = moveForward;
diff --git a/src/js/net/minecraft/client/gui/Gui.js b/src/js/net/minecraft/client/gui/Gui.js
index ae0d777..7d1afd3 100644
--- a/src/js/net/minecraft/client/gui/Gui.js
+++ b/src/js/net/minecraft/client/gui/Gui.js
@@ -1,5 +1,7 @@
 window.Gui = class {
 
+    static FONT = "normal 20px Minecraftia";
+
     drawRect(stack, left, top, right, bottom, color, alpha = 1) {
         stack.save();
         stack.fillStyle = color;
@@ -8,18 +10,28 @@ window.Gui = class {
         stack.restore();
     }
 
-    drawString(stack, string, x, y, color) {
-        this._drawString(stack, string, x, y, color, 0, false);
+    drawCenteredString(stack, string, x, y, color = 'white') {
+        this._drawString(stack, string, x + this.getStringWidth(stack, string) / 2, y, color, 1);
     }
 
-    _drawString(stack, string, x, y, color, alignment, bold) {
-        let size = 24;
-        stack.font = (bold ? "bold" : "normal") + " " + size + "px Minecraftia";
-        stack.fillStyle = color;
+    drawString(stack, string, x, y, color = 'white') {
+        this._drawString(stack, string, x, y, color, 0);
+    }
+
+    _drawString(stack, string, x, y, color, alignment) {
+        stack.font = Gui.FONT;
+        stack.fillStyle = 'black';
         stack.textAlign = alignment === 0 ? "center" : alignment < 0 ? "left" : "right";
+        stack.fillText(string, x + 2, y + 2);
+        stack.fillStyle = color;
         stack.fillText(string, x, y);
     }
 
+    getStringWidth(stack, string) {
+        stack.font = Gui.FONT;
+        return stack.measureText(string).width;
+    }
+
     drawTexture(stack, texture, x, y, width, height, alpha = 1.0) {
         this.drawSprite(stack, texture, 0, 0, 256, 256, x, y, width, height, alpha);
     }
@@ -42,7 +54,7 @@ window.Gui = class {
         stack.restore();
     }
 
-    loadTexture(path) {
+    static loadTexture(path) {
         let img = new Image();
         img.src = path;
         return img;
diff --git a/src/js/net/minecraft/client/gui/GuiScreen.js b/src/js/net/minecraft/client/gui/GuiScreen.js
index f802d7d..84e62a7 100644
--- a/src/js/net/minecraft/client/gui/GuiScreen.js
+++ b/src/js/net/minecraft/client/gui/GuiScreen.js
@@ -1,13 +1,28 @@
 window.GuiScreen = class extends Gui {
 
-    init(minecraft, width, height) {
+    constructor() {
+        super();
+
+        this.buttonList = [];
+    }
+
+    setup(minecraft, width, height) {
         this.minecraft = minecraft;
         this.width = width;
         this.height = height;
+
+        this.init();
+    }
+
+    init() {
+        this.buttonList = [];
     }
 
     drawScreen(stack, mouseX, mouseY, partialTicks) {
-
+        for (let i in this.buttonList) {
+            let button = this.buttonList[i];
+            button.render(stack, mouseX, mouseY, partialTicks);
+        }
     }
 
     keyTyped(code) {
@@ -18,4 +33,14 @@ window.GuiScreen = class extends Gui {
         return false;
     }
 
+    mouseClicked(mouseX, mouseY, mouseButton) {
+        for (let i in this.buttonList) {
+            let button = this.buttonList[i];
+
+            if (button.isMouseOver(mouseX, mouseY)) {
+                button.mouseClicked(mouseX, mouseY, mouseButton);
+            }
+        }
+    }
+
 }
\ No newline at end of file
diff --git a/src/js/net/minecraft/client/gui/IngameOverlay.js b/src/js/net/minecraft/client/gui/IngameOverlay.js
index 6344c60..723ef3a 100644
--- a/src/js/net/minecraft/client/gui/IngameOverlay.js
+++ b/src/js/net/minecraft/client/gui/IngameOverlay.js
@@ -4,7 +4,7 @@ window.IngameOverlay = class extends Gui {
         super();
         this.window = window;
 
-        this.textureCrosshair = this.loadTexture("icons.png");
+        this.textureCrosshair = Gui.loadTexture("icons.png");
     }
 
     render(stack, mouseX, mouseY, partialTicks) {
diff --git a/src/js/net/minecraft/client/gui/screens/GuiIngameMenu.js b/src/js/net/minecraft/client/gui/screens/GuiIngameMenu.js
index fe80bac..fdab5eb 100644
--- a/src/js/net/minecraft/client/gui/screens/GuiIngameMenu.js
+++ b/src/js/net/minecraft/client/gui/screens/GuiIngameMenu.js
@@ -4,8 +4,23 @@ window.GuiIngameMenu = class extends GuiScreen {
         super();
     }
 
-    drawScreen(stack, mouseX, mouseY, partialTicks) {
+    init() {
+        super.init();
 
+        let scope = this;
+        this.buttonList.push(new GuiButton("Back to game", this.width / 2 - 100 * 3, this.height / 2 - 50 * 3, 200 * 3, 20 * 3, function () {
+            scope.minecraft.displayScreen(null);
+        }));
+    }
+
+    drawScreen(stack, mouseX, mouseY, partialTicks) {
+        // Background
+        this.drawRect(stack, 0, 0, this.width, this.height, 'black', 0.6);
+
+        // Title
+        this.drawCenteredString(stack, "Game paused", this.width / 2, 100);
+
+        super.drawScreen(stack, mouseX, mouseY, partialTicks);
     }
 
 }
\ No newline at end of file
diff --git a/src/js/net/minecraft/client/gui/screens/GuiLoadingScreen.js b/src/js/net/minecraft/client/gui/screens/GuiLoadingScreen.js
index 4007f75..42e9b7a 100644
--- a/src/js/net/minecraft/client/gui/screens/GuiLoadingScreen.js
+++ b/src/js/net/minecraft/client/gui/screens/GuiLoadingScreen.js
@@ -3,7 +3,7 @@ window.GuiLoadingScreen = class extends GuiScreen {
     constructor() {
         super();
 
-        this.textureBackground = this.loadTexture("background.png");
+        this.textureBackground = Gui.loadTexture("background.png");
     }
 
     drawScreen(stack, mouseX, mouseY, partialTicks) {
@@ -35,6 +35,8 @@ window.GuiLoadingScreen = class extends GuiScreen {
             this.height / 2 + progressHeight / 2,
             '#80ff80',
         );
+
+        super.drawScreen(stack, mouseX, mouseY, partialTicks);
     }
 
     setTitle(title) {
diff --git a/src/js/net/minecraft/client/gui/widgets/GuiButton.js b/src/js/net/minecraft/client/gui/widgets/GuiButton.js
new file mode 100644
index 0000000..952e373
--- /dev/null
+++ b/src/js/net/minecraft/client/gui/widgets/GuiButton.js
@@ -0,0 +1,30 @@
+window.GuiButton = class extends Gui {
+
+    static textureGui = Gui.loadTexture("gui.png");
+
+    constructor(string, x, y, width, height, callback) {
+        super();
+
+        this.string = string;
+        this.x = x;
+        this.y = y;
+        this.width = width;
+        this.height = height;
+        this.callback = callback;
+    }
+
+    render(stack, mouseX, mouseY, partialTicks) {
+        let mouseOver = this.isMouseOver(mouseX, mouseY);
+        this.drawSprite(stack, GuiButton.textureGui, 0, mouseOver ? 40 : 20, 200, 20, this.x, this.y, this.width, this.height);
+        this.drawCenteredString(stack, this.string, this.x + this.width / 2, this.y + this.height / 2 + 17);
+    }
+
+    mouseClicked(mouseX, mouseY, mouseButton) {
+        this.callback();
+    }
+
+    isMouseOver(mouseX, mouseY) {
+        return mouseX > this.x && mouseX < this.x + this.width && mouseY > this.y && mouseY < this.y + this.height;
+    }
+
+}
\ No newline at end of file
diff --git a/src/js/net/minecraft/client/world/World.js b/src/js/net/minecraft/client/world/World.js
index 7d8b3cf..4c64e1c 100644
--- a/src/js/net/minecraft/client/world/World.js
+++ b/src/js/net/minecraft/client/world/World.js
@@ -13,6 +13,16 @@ window.World = class {
 
         // Load world
         this.generator = new WorldGenerator(this, Date.now() % 100000);
+
+        // Update lights async
+        let scope = this;
+        setInterval(function () {
+            let i = 1000;
+            while (scope.lightUpdateQueue.length >= 10 && i > 0) {
+                i--;
+                scope.lightUpdateQueue.shift().updateBlockLightning(scope);
+            }
+        }, 1);
     }
 
     onTick() {
@@ -83,22 +93,7 @@ window.World = class {
     updateLights() {
         let scope = this;
 
-        if (this.lightUpdateQueue.length > 10) {
-            // Update lights async
-            setTimeout(function () {
-                // Update lights in queue
-                let i = 5000;
-                while (scope.lightUpdateQueue.length > 0) {
-                    if (i <= 0) {
-                        break;
-                    }
-
-                    let meta = scope.lightUpdateQueue.shift();
-                    meta.updateBlockLightning(scope);
-                    i--;
-                }
-            }, 0);
-        } else {
+        if (this.lightUpdateQueue.length < 10) {
             // Update lights in queue
             let i = 10;
             while (scope.lightUpdateQueue.length > 0) {
diff --git a/src/resources/gui.png b/src/resources/gui.png
new file mode 100644
index 0000000..973dd0d
Binary files /dev/null and b/src/resources/gui.png differ
diff --git a/src/resources/terrain.png b/src/resources/terrain.png
index e0e796f..20e058b 100644
Binary files a/src/resources/terrain.png and b/src/resources/terrain.png differ
diff --git a/src/start.js b/src/start.js
index 84a2ccc..2454473 100644
--- a/src/start.js
+++ b/src/start.js
@@ -61,6 +61,7 @@ loadScripts([
     "src/js/net/minecraft/util/Keyboard.js",
     "src/js/net/minecraft/client/gui/Gui.js",
     "src/js/net/minecraft/client/gui/GuiScreen.js",
+    "src/js/net/minecraft/client/gui/widgets/GuiButton.js",
     "src/js/net/minecraft/client/gui/IngameOverlay.js",
     "src/js/net/minecraft/client/gui/screens/GuiLoadingScreen.js",
     "src/js/net/minecraft/client/gui/screens/GuiIngameMenu.js",
diff --git a/style.css b/style.css
index 2ce76c1..cba8926 100644
--- a/style.css
+++ b/style.css
@@ -37,6 +37,7 @@ body {
     /* Font */
     font-size: 25px;
     font-family: "Minecraftia", sans-serif;
+    text-shadow: 2px 2px #000000;
     color: white;
 }