diff --git a/README.md b/README.md
index d6eca97..2525074 100644
--- a/README.md
+++ b/README.md
@@ -26,3 +26,4 @@ cd build/android
 [spirv-reflect](https://github.com/KhronosGroup/SPIRV-Reflect),
 [vma](https://github.com/GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator),
 [vulkan-sdk](https://vulkan.lunarg.com)
+[volk](https://github.com/zeux/volk)
diff --git a/src/demo/demo.h b/src/demo/demo.h
index 89962e3..b3ec1ed 100644
--- a/src/demo/demo.h
+++ b/src/demo/demo.h
@@ -18,20 +18,20 @@
 
 // #define LOAD_TEST
 
-class Demo : public eng::Game {
+class Demo final : public eng::Game {
  public:
   Demo();
-  ~Demo() override;
+  ~Demo() final;
 
-  bool Initialize() override;
+  bool Initialize() final;
 
-  void Update(float delta_time) override;
+  void Update(float delta_time) final;
 
-  void ContextLost() override;
+  void ContextLost() final;
 
-  void LostFocus() override;
+  void LostFocus() final;
 
-  void GainedFocus(bool from_interstitial_ad) override;
+  void GainedFocus(bool from_interstitial_ad) final;
 
   void AddScore(size_t score);
 
diff --git a/src/demo/sky_quad.h b/src/demo/sky_quad.h
index 4775669..400cd46 100644
--- a/src/demo/sky_quad.h
+++ b/src/demo/sky_quad.h
@@ -27,14 +27,14 @@ class SkyQuad : public eng::Animatable {
   void Update(float delta_time);
 
   // Animatable interface.
-  void SetFrame(size_t frame) override {}
-  size_t GetFrame() const override { return 0; }
-  size_t GetNumFrames() const override { return 0; }
-  void SetColor(const base::Vector4f& color) override { nebula_color_ = color; }
-  base::Vector4f GetColor() const override { return nebula_color_; }
+  void SetFrame(size_t frame) final {}
+  size_t GetFrame() const final { return 0; }
+  size_t GetNumFrames() const final { return 0; }
+  void SetColor(const base::Vector4f& color) final { nebula_color_ = color; }
+  base::Vector4f GetColor() const final { return nebula_color_; }
 
   // Drawable interface.
-  void Draw(float frame_frac) override;
+  void Draw(float frame_frac) final;
 
   void ContextLost();
 
diff --git a/src/engine/audio/audio_oboe.h b/src/engine/audio/audio_oboe.h
index 7b10b7f..0470365 100644
--- a/src/engine/audio/audio_oboe.h
+++ b/src/engine/audio/audio_oboe.h
@@ -25,17 +25,17 @@ class AudioOboe : public AudioBase {
   int GetHardwareSampleRate();
 
  private:
-  class StreamCallback : public oboe::AudioStreamCallback {
+  class StreamCallback final : public oboe::AudioStreamCallback {
    public:
     StreamCallback(AudioOboe* audio);
-    ~StreamCallback() override;
+    ~StreamCallback() final;
 
     oboe::DataCallbackResult onAudioReady(oboe::AudioStream* oboe_stream,
                                           void* audio_data,
-                                          int32_t num_frames) override;
+                                          int32_t num_frames) final;
 
     void onErrorAfterClose(oboe::AudioStream* oboe_stream,
-                           oboe::Result error) override;
+                           oboe::Result error) final;
 
    private:
     AudioOboe* audio_;
diff --git a/src/engine/game_factory.h b/src/engine/game_factory.h
index 7060c65..3cf513c 100644
--- a/src/engine/game_factory.h
+++ b/src/engine/game_factory.h
@@ -38,14 +38,14 @@ class GameFactoryBase {
 };
 
 template <typename Type>
-class GameFactory : public GameFactoryBase {
+class GameFactory final : public GameFactoryBase {
  public:
-  ~GameFactory() override = default;
+  ~GameFactory() final = default;
 
  private:
   using GameType = Type;
 
-  std::unique_ptr<Game> CreateGame() override {
+  std::unique_ptr<Game> CreateGame() final {
     return std::make_unique<GameType>();
   }
 };
diff --git a/src/engine/image.cc b/src/engine/image.cc
index 846e775..f33d266 100644
--- a/src/engine/image.cc
+++ b/src/engine/image.cc
@@ -6,9 +6,9 @@
 #include "base/interpolation.h"
 #include "base/log.h"
 #include "base/misc.h"
-#include "third_party/texture_compressor/texture_compressor.h"
 #include "engine/engine.h"
 #include "engine/platform/asset_file.h"
+#include "third_party/texture_compressor/texture_compressor.h"
 
 // This 3rd party library is written in C and uses malloc, which means that we
 // have to do the same.
diff --git a/src/engine/image_quad.h b/src/engine/image_quad.h
index 7da51e7..e735a70 100644
--- a/src/engine/image_quad.h
+++ b/src/engine/image_quad.h
@@ -14,10 +14,10 @@ namespace eng {
 class Shader;
 class Texture;
 
-class ImageQuad : public Animatable {
+class ImageQuad final : public Animatable {
  public:
   ImageQuad();
-  ~ImageQuad() override;
+  ~ImageQuad() final;
 
   void Create(const std::string& asset_name,
               std::array<int, 2> num_frames = {1, 1},
@@ -36,14 +36,14 @@ class ImageQuad : public Animatable {
   }
 
   // Animatable interface.
-  void SetFrame(size_t frame) override;
-  size_t GetFrame() const override { return current_frame_; }
-  size_t GetNumFrames() const override;
-  void SetColor(const base::Vector4f& color) override { color_ = color; }
-  base::Vector4f GetColor() const override { return color_; }
+  void SetFrame(size_t frame) final;
+  size_t GetFrame() const final { return current_frame_; }
+  size_t GetNumFrames() const final;
+  void SetColor(const base::Vector4f& color) final { color_ = color; }
+  base::Vector4f GetColor() const final { return color_; }
 
   // Drawable interface.
-  void Draw(float frame_frac) override;
+  void Draw(float frame_frac) final;
 
  private:
   using UniformValue = std::variant<base::Vector2f,
diff --git a/src/engine/mesh.cc b/src/engine/mesh.cc
index fb16a90..a3accc1 100644
--- a/src/engine/mesh.cc
+++ b/src/engine/mesh.cc
@@ -3,9 +3,9 @@
 #include <string.h>
 
 #include "base/log.h"
-#include "third_party/jsoncpp/json.h"
 #include "engine/engine.h"
 #include "engine/platform/asset_file.h"
+#include "third_party/jsoncpp/json.h"
 
 namespace eng {
 
diff --git a/src/engine/platform/platform.cc b/src/engine/platform/platform.cc
index ff47a6c..2f64235 100644
--- a/src/engine/platform/platform.cc
+++ b/src/engine/platform/platform.cc
@@ -7,7 +7,7 @@
 #include "engine/renderer/opengl/renderer_opengl.h"
 #include "engine/renderer/vulkan/renderer_vulkan.h"
 
-#define VULKAN_RENDERER
+#define USE_VULKAN_RENDERER 1
 
 using namespace base;
 
@@ -31,7 +31,7 @@ void Platform::InitializeCommon() {
     throw internal_error;
   }
 
-#if defined(VULKAN_RENDERER)
+#if (USE_VULKAN_RENDERER == 1)
   renderer_ = std::make_unique<RendererVulkan>();
 #else
   renderer_ = std::make_unique<RendererOpenGL>();
diff --git a/src/engine/renderer/opengl/renderer_opengl.h b/src/engine/renderer/opengl/renderer_opengl.h
index 27b4490..04646d0 100644
--- a/src/engine/renderer/opengl/renderer_opengl.h
+++ b/src/engine/renderer/opengl/renderer_opengl.h
@@ -35,63 +35,60 @@ namespace eng {
 
 struct RenderCommand;
 
-class RendererOpenGL : public Renderer {
+class RendererOpenGL final : public Renderer {
  public:
   RendererOpenGL();
-  ~RendererOpenGL() override;
+  ~RendererOpenGL() final;
 
 #if defined(__ANDROID__)
-  bool Initialize(ANativeWindow* window) override;
+  bool Initialize(ANativeWindow* window) final;
 #elif defined(__linux__)
-  bool Initialize(Display* display, Window window) override;
+  bool Initialize(Display* display, Window window) final;
 #endif
 
-  void Shutdown() override;
+  void Shutdown() final;
 
-  uint64_t CreateGeometry(std::unique_ptr<Mesh> mesh) override;
-  void DestroyGeometry(uint64_t resource_id) override;
-  void Draw(uint64_t resource_id) override;
+  uint64_t CreateGeometry(std::unique_ptr<Mesh> mesh) final;
+  void DestroyGeometry(uint64_t resource_id) final;
+  void Draw(uint64_t resource_id) final;
 
-  uint64_t CreateTexture() override;
-  void UpdateTexture(uint64_t resource_id,
-                     std::unique_ptr<Image> image) override;
-  void DestroyTexture(uint64_t resource_id) override;
-  void ActivateTexture(uint64_t resource_id) override;
+  uint64_t CreateTexture() final;
+  void UpdateTexture(uint64_t resource_id, std::unique_ptr<Image> image) final;
+  void DestroyTexture(uint64_t resource_id) final;
+  void ActivateTexture(uint64_t resource_id) final;
 
   uint64_t CreateShader(std::unique_ptr<ShaderSource> source,
                         const VertexDescripton& vertex_description,
                         Primitive primitive,
-                        bool enable_depth_test) override;
-  void DestroyShader(uint64_t resource_id) override;
-  void ActivateShader(uint64_t resource_id) override;
+                        bool enable_depth_test) final;
+  void DestroyShader(uint64_t resource_id) final;
+  void ActivateShader(uint64_t resource_id) final;
 
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Vector2f& val) override;
+                  const base::Vector2f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Vector3f& val) override;
+                  const base::Vector3f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Vector4f& val) override;
+                  const base::Vector4f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Matrix4f& val) override;
+                  const base::Matrix4f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  float val) override;
-  void SetUniform(uint64_t resource_id,
-                  const std::string& name,
-                  int val) override;
-  void UploadUniforms(uint64_t resource_id) override {}
+                  float val) final;
+  void SetUniform(uint64_t resource_id, const std::string& name, int val) final;
+  void UploadUniforms(uint64_t resource_id) final {}
 
-  void PrepareForDrawing() override {}
-  void Present() override;
+  void PrepareForDrawing() final {}
+  void Present() final;
 
-  size_t GetAndResetFPS() override;
+  size_t GetAndResetFPS() final;
 
 #if defined(__linux__) && !defined(__ANDROID__)
-  XVisualInfo* GetXVisualInfo(Display* display) override;
+  XVisualInfo* GetXVisualInfo(Display* display) final;
 #endif
 
  private:
diff --git a/src/engine/renderer/vulkan/renderer_vulkan.cc b/src/engine/renderer/vulkan/renderer_vulkan.cc
index 4964429..d9e8ef8 100644
--- a/src/engine/renderer/vulkan/renderer_vulkan.cc
+++ b/src/engine/renderer/vulkan/renderer_vulkan.cc
@@ -466,13 +466,13 @@ void RendererVulkan::UpdateTexture(uint64_t resource_id,
       (it->second.width != image->GetWidth() ||
        it->second.height != image->GetHeight())) {
     // Size mismatch. Recreate the texture.
-    FreeTexture(std::move(it->second.image), it->second.view,
-                std::move(it->second.desc_set));
+    FreeImage(std::move(it->second.image), it->second.view,
+              std::move(it->second.desc_set));
     it->second = {};
   }
 
   if (it->second.view == VK_NULL_HANDLE) {
-    CreateTexture(it->second.image, it->second.view, it->second.desc_set,
+    AllocateImage(it->second.image, it->second.view, it->second.desc_set,
                   format, image->GetWidth(), image->GetHeight(),
                   VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT,
                   VMA_MEMORY_USAGE_GPU_ONLY);
@@ -514,8 +514,8 @@ void RendererVulkan::DestroyTexture(uint64_t resource_id) {
   if (it == textures_.end())
     return;
 
-  FreeTexture(std::move(it->second.image), it->second.view,
-              std::move(it->second.desc_set));
+  FreeImage(std::move(it->second.image), it->second.view,
+            std::move(it->second.desc_set));
   textures_.erase(it);
 }
 
@@ -1458,7 +1458,7 @@ void RendererVulkan::BufferMemoryBarrier(VkBuffer buffer,
                        &buffer_mem_barrier, 0, nullptr);
 }
 
-bool RendererVulkan::CreateTexture(Buffer<VkImage>& image,
+bool RendererVulkan::AllocateImage(Buffer<VkImage>& image,
                                    VkImageView& view,
                                    DescSet& desc_set,
                                    VkFormat format,
@@ -1575,9 +1575,9 @@ bool RendererVulkan::CreateTexture(Buffer<VkImage>& image,
   return true;
 }
 
-void RendererVulkan::FreeTexture(Buffer<VkImage> image,
-                                 VkImageView image_view,
-                                 DescSet desc_set) {
+void RendererVulkan::FreeImage(Buffer<VkImage> image,
+                               VkImageView image_view,
+                               DescSet desc_set) {
   frames_[current_frame_].images_to_destroy.push_back(
       std::make_tuple(std::move(image), image_view));
   frames_[current_frame_].desc_sets_to_destroy.push_back(std::move(desc_set));
diff --git a/src/engine/renderer/vulkan/renderer_vulkan.h b/src/engine/renderer/vulkan/renderer_vulkan.h
index 3bcd1ba..1796a92 100644
--- a/src/engine/renderer/vulkan/renderer_vulkan.h
+++ b/src/engine/renderer/vulkan/renderer_vulkan.h
@@ -20,63 +20,60 @@ namespace eng {
 
 class Image;
 
-class RendererVulkan : public Renderer {
+class RendererVulkan final : public Renderer {
  public:
   RendererVulkan();
-  ~RendererVulkan() override;
+  ~RendererVulkan() final;
 
 #if defined(__ANDROID__)
-  bool Initialize(ANativeWindow* window) override;
+  bool Initialize(ANativeWindow* window) final;
 #elif defined(__linux__)
-  bool Initialize(Display* display, Window window) override;
+  bool Initialize(Display* display, Window window) final;
 #endif
 
-  void Shutdown() override;
+  void Shutdown() final;
 
-  uint64_t CreateGeometry(std::unique_ptr<Mesh> mesh) override;
-  void DestroyGeometry(uint64_t resource_id) override;
-  void Draw(uint64_t resource_id) override;
+  uint64_t CreateGeometry(std::unique_ptr<Mesh> mesh) final;
+  void DestroyGeometry(uint64_t resource_id) final;
+  void Draw(uint64_t resource_id) final;
 
-  uint64_t CreateTexture() override;
-  void UpdateTexture(uint64_t resource_id,
-                     std::unique_ptr<Image> image) override;
-  void DestroyTexture(uint64_t resource_id) override;
-  void ActivateTexture(uint64_t resource_id) override;
+  uint64_t CreateTexture() final;
+  void UpdateTexture(uint64_t resource_id, std::unique_ptr<Image> image) final;
+  void DestroyTexture(uint64_t resource_id) final;
+  void ActivateTexture(uint64_t resource_id) final;
 
   uint64_t CreateShader(std::unique_ptr<ShaderSource> source,
                         const VertexDescripton& vertex_description,
                         Primitive primitive,
-                        bool enable_depth_test) override;
-  void DestroyShader(uint64_t resource_id) override;
-  void ActivateShader(uint64_t resource_id) override;
+                        bool enable_depth_test) final;
+  void DestroyShader(uint64_t resource_id) final;
+  void ActivateShader(uint64_t resource_id) final;
 
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Vector2f& val) override;
+                  const base::Vector2f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Vector3f& val) override;
+                  const base::Vector3f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Vector4f& val) override;
+                  const base::Vector4f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  const base::Matrix4f& val) override;
+                  const base::Matrix4f& val) final;
   void SetUniform(uint64_t resource_id,
                   const std::string& name,
-                  float val) override;
-  void SetUniform(uint64_t resource_id,
-                  const std::string& name,
-                  int val) override;
-  void UploadUniforms(uint64_t resource_id) override;
+                  float val) final;
+  void SetUniform(uint64_t resource_id, const std::string& name, int val) final;
+  void UploadUniforms(uint64_t resource_id) final;
 
-  void PrepareForDrawing() override;
-  void Present() override;
+  void PrepareForDrawing() final;
+  void Present() final;
 
-  size_t GetAndResetFPS() override;
+  size_t GetAndResetFPS() final;
 
 #if defined(__linux__) && !defined(__ANDROID__)
-  XVisualInfo* GetXVisualInfo(Display* display) override;
+  XVisualInfo* GetXVisualInfo(Display* display) final;
 #endif
 
  private:
@@ -224,7 +221,7 @@ class RendererVulkan : public Renderer {
                            VkAccessFlags src_access,
                            VkAccessFlags dst_sccess);
 
-  bool CreateTexture(Buffer<VkImage>& image,
+  bool AllocateImage(Buffer<VkImage>& image,
                      VkImageView& view,
                      DescSet& desc_set,
                      VkFormat format,
@@ -232,9 +229,9 @@ class RendererVulkan : public Renderer {
                      int height,
                      VkImageUsageFlags usage,
                      VmaMemoryUsage mapping);
-  void FreeTexture(Buffer<VkImage> image,
-                   VkImageView image_view,
-                   DescSet desc_set);
+  void FreeImage(Buffer<VkImage> image,
+                 VkImageView image_view,
+                 DescSet desc_set);
   void UpdateImage(VkImage image,
                    VkFormat format,
                    const uint8_t* data,
diff --git a/src/engine/solid_quad.h b/src/engine/solid_quad.h
index faa3cbc..2bc393a 100644
--- a/src/engine/solid_quad.h
+++ b/src/engine/solid_quad.h
@@ -5,20 +5,20 @@
 
 namespace eng {
 
-class SolidQuad : public Animatable {
+class SolidQuad final : public Animatable {
  public:
   SolidQuad() = default;
-  ~SolidQuad() override = default;
+  ~SolidQuad() final = default;
 
   // Animatable interface.
-  void SetFrame(size_t frame) override {}
-  size_t GetFrame() const override { return 0; }
-  size_t GetNumFrames() const override { return 0; }
-  void SetColor(const base::Vector4f& color) override { color_ = color; }
-  base::Vector4f GetColor() const override { return color_; }
+  void SetFrame(size_t frame) final {}
+  size_t GetFrame() const final { return 0; }
+  size_t GetNumFrames() const final { return 0; }
+  void SetColor(const base::Vector4f& color) final { color_ = color; }
+  base::Vector4f GetColor() const final { return color_; }
 
   // Drawable interface.
-  void Draw(float frame_frac) override;
+  void Draw(float frame_frac) final;
 
  private:
   base::Vector4f color_ = {1, 1, 1, 1};