diff --git a/modules/engine/include/engine/core/application.hpp b/modules/engine/include/engine/core/application.hpp
index 00917e7..6769e26 100644
--- a/modules/engine/include/engine/core/application.hpp
+++ b/modules/engine/include/engine/core/application.hpp
@@ -1,16 +1,13 @@
 #pragma once
 
 #include <engine/base/base.hpp>
-#include <engine/debug/instrumentor.hpp>
 #include <engine/input/input.hpp>
 #include <engine/layer/layer_stack.hpp>
-#include <engine/utils/resource_manager.hpp>
 
 namespace Light {
 
 class Window;
 class Event;
-class Instrumentor;
 
 class Application
 {
@@ -35,15 +32,7 @@ private:
 
 	void log_debug_data();
 
-	static Application *s_context;
-
-	Scope<Instrumentor> m_instrumentor;
-
 	Scope<LayerStack> m_layer_stack;
-
-	Scope<Input> m_input;
-
-	Scope<ResourceManager> m_resource_manager;
 };
 
 extern Light::Scope<Application> create_application();
diff --git a/modules/engine/include/engine/debug/instrumentor.hpp b/modules/engine/include/engine/debug/instrumentor.hpp
index b555206..9bb6939 100644
--- a/modules/engine/include/engine/debug/instrumentor.hpp
+++ b/modules/engine/include/engine/debug/instrumentor.hpp
@@ -16,30 +16,32 @@ struct ScopeProfileResult
 class Instrumentor
 {
 public:
-	static Scope<Instrumentor> create();
+	static auto instance() -> Instrumentor &
+	{
+		static auto instance = Instrumentor {};
+		return instance;
+	}
 
 	static void begin_session(const std::string &outputPath)
 	{
-		s_context->begin_session_impl(outputPath);
+		instance().begin_session_impl(outputPath);
 	}
 	static void end_session()
 	{
-		s_context->end_session_impl();
+		instance().end_session_impl();
 	}
 
 	static void submit_scope_profile(const ScopeProfileResult &profileResult)
 	{
-		s_context->submit_scope_profile_impl(profileResult);
+		instance().submit_scope_profile_impl(profileResult);
 	}
 
 private:
-	static Instrumentor *s_context;
-
 	std::ofstream m_output_file_stream;
 
-	unsigned int m_current_session_count{0u};
+	unsigned int m_current_session_count { 0u };
 
-	Instrumentor();
+	Instrumentor() = default;
 
 	void begin_session_impl(const std::string &outputPath);
 
diff --git a/modules/engine/include/engine/input/input.hpp b/modules/engine/include/engine/input/input.hpp
index a6b5c85..c638e94 100644
--- a/modules/engine/include/engine/input/input.hpp
+++ b/modules/engine/include/engine/input/input.hpp
@@ -11,29 +11,35 @@ class Event;
 class Input
 {
 public:
-	static auto create() -> Scope<Input>;
+	static auto instance() -> Input &
+	{
+		static auto instance = Input {};
+		return instance;
+	}
 
 	static void receive_user_interface_events(bool receive, bool toggle = false)
 	{
-		s_context->receive_user_interface_events_impl(receive, toggle);
+		instance().receive_user_interface_events_impl(receive, toggle);
 	}
+
 	static void receive_game_events(bool receive, bool toggle = false)
 	{
-		s_context->receieve_game_events_impl(receive, toggle);
+		instance().receieve_game_events_impl(receive, toggle);
 	}
 
 	static auto get_keyboard_key(int code) -> bool
 	{
-		return s_context->m_keyboad_keys[code];
-	}
-	static auto get_mouse_button(int code) -> bool
-	{
-		return s_context->m_mouse_buttons[code];
+		return instance().m_keyboad_keys[code];
 	}
 
-	static auto get_mouse_position(int  /*code*/) -> const glm::vec2 &
+	static auto get_mouse_button(int code) -> bool
 	{
-		return s_context->m_mouse_position;
+		return instance().m_mouse_buttons[code];
+	}
+
+	static auto get_mouse_position(int /*code*/) -> const glm::vec2 &
+	{
+		return instance().m_mouse_position;
 	}
 
 	void on_event(const Event &inputEvent);
@@ -49,22 +55,6 @@ public:
 	}
 
 private:
-	static Input *s_context;
-
-	std::array<bool, 348> m_keyboad_keys{};
-
-	std::array<bool, 8> m_mouse_buttons{};
-
-	glm::vec2 m_mouse_position;
-
-	glm::vec2 m_mouse_delta;
-
-	float m_mouse_wheel_delta{};
-
-	bool m_user_interface_events{true};
-
-	bool m_game_events{true};
-
 	Input();
 
 	void receive_user_interface_events_impl(bool receive, bool toggle = false);
@@ -72,6 +62,20 @@ private:
 	void receieve_game_events_impl(bool receive, bool toggle = false);
 
 	void restart_input_state();
+
+	std::array<bool, 348> m_keyboad_keys {};
+
+	std::array<bool, 8> m_mouse_buttons {};
+
+	glm::vec2 m_mouse_position;
+
+	glm::vec2 m_mouse_delta;
+
+	float m_mouse_wheel_delta {};
+
+	bool m_user_interface_events { true };
+
+	bool m_game_events { true };
 };
 
 } // namespace Light
diff --git a/modules/engine/include/engine/layer/layer_stack.hpp b/modules/engine/include/engine/layer/layer_stack.hpp
index 71992d7..686301a 100644
--- a/modules/engine/include/engine/layer/layer_stack.hpp
+++ b/modules/engine/include/engine/layer/layer_stack.hpp
@@ -10,7 +10,11 @@ class Event;
 class LayerStack /* singleton */
 {
 public:
-	static auto create() -> Scope<LayerStack>;
+	static auto instance() -> LayerStack &
+	{
+		static auto instance = LayerStack {};
+		return instance;
+	}
 
 	~LayerStack();
 
@@ -18,17 +22,17 @@ public:
 	template<typename t, typename... Args>
 	static void emplace_layer(Args &&...args)
 	{
-		s_context->attach_layer_impl(new t((args)...));
+		instance().attach_layer_impl(new t((args)...));
 	}
 
 	static void attach_layer(Layer *layer)
 	{
-		s_context->attach_layer_impl(layer);
+		instance().attach_layer_impl(layer);
 	}
 
 	static void detach_layer(Layer *layer)
 	{
-		s_context->detach_layer_impl(layer);
+		instance().detach_layer_impl(layer);
 	}
 
 	auto is_empty() -> bool
@@ -57,15 +61,13 @@ public:
 	}
 
 private:
-	static LayerStack *s_context;
-
 	std::vector<Layer *> m_layers;
 
 	std::vector<Layer *>::iterator m_begin;
 
 	std::vector<Layer *>::iterator m_end;
 
-	LayerStack();
+	LayerStack() = default;
 
 	void attach_layer_impl(Layer *layer);
 
diff --git a/modules/engine/include/engine/utils/resource_manager.hpp b/modules/engine/include/engine/utils/resource_manager.hpp
index 61448d0..58e5b1e 100644
--- a/modules/engine/include/engine/utils/resource_manager.hpp
+++ b/modules/engine/include/engine/utils/resource_manager.hpp
@@ -11,7 +11,11 @@ class SharedContext;
 class ResourceManager
 {
 public:
-	static auto create() -> Scope<ResourceManager>;
+	static auto instance() -> ResourceManager &
+	{
+		static auto instance = ResourceManager {};
+		return instance;
+	}
 
 	static void load_shader(
 	    const std::string &name,
@@ -19,7 +23,7 @@ public:
 	    const std::string &pixelPath
 	)
 	{
-		s_context->load_shader_impl(name, vertexPath, pixelPath);
+		instance().load_shader_impl(name, vertexPath, pixelPath);
 	}
 
 	static void load_texture(
@@ -28,32 +32,26 @@ public:
 	    unsigned int desiredComponents = 4u
 	)
 	{
-		s_context->load_texture_impl(name, path, desiredComponents);
+		instance().load_texture_impl(name, path, desiredComponents);
 	}
 
 	static void release_texture(const std::string &name)
 	{
-		s_context->release_texture_impl(name);
+		instance().release_texture_impl(name);
 	}
 
 	static auto get_shader(const std::string &name) -> Ref<Shader>
 	{
-		return s_context->m_shaders[name];
+		return instance().m_shaders[name];
 	}
 
 	static auto get_texture(const std::string &name) -> Ref<Texture>
 	{
-		return s_context->m_textures[name];
+		return instance().m_textures[name];
 	}
 
 private:
-	static ResourceManager *s_context;
-
-	std::unordered_map<std::string, Ref<Shader>> m_shaders;
-
-	std::unordered_map<std::string, Ref<Texture>> m_textures;
-
-	ResourceManager();
+	ResourceManager() = default;
 
 	void load_shader_impl(
 	    const std::string &name,
@@ -68,6 +66,10 @@ private:
 	);
 
 	void release_texture_impl(const std::string &name);
+
+	std::unordered_map<std::string, Ref<Shader>> m_shaders;
+
+	std::unordered_map<std::string, Ref<Texture>> m_textures;
 };
 
 } // namespace Light
diff --git a/modules/engine/src/core/application.cpp b/modules/engine/src/core/application.cpp
index 79f87ba..5861369 100644
--- a/modules/engine/src/core/application.cpp
+++ b/modules/engine/src/core/application.cpp
@@ -12,34 +12,23 @@
 
 namespace Light {
 
-Application *Application::s_context = nullptr;
-
-Application::Application()
-    : m_instrumentor(nullptr)
-    , m_layer_stack(nullptr)
-    , m_input(nullptr)
-    , m_window(nullptr)
+Application::Application(): m_window(nullptr)
 {
-	lt_assert(!s_context, "Repeated singleton construction");
-	s_context = this;
+	static auto constructed = false;
+	lt_assert(!constructed, "Application constructed twice");
+	constructed = true;
 
 	log_debug_data();
 
-	m_instrumentor = Instrumentor::create();
 	Light::Instrumentor::begin_session("Logs/ProfileResults_Startup.json");
 
-	m_layer_stack = LayerStack::create();
-	m_input = Input::create();
-
-	m_resource_manager = ResourceManager::create();
-
-	m_window = Window::create([this](auto && PH1) { on_event(std::forward<decltype(PH1)>(PH1)); });
+	m_window = Window::create([this](auto &&PH1) { on_event(std::forward<decltype(PH1)>(PH1)); });
 }
 
 Application::~Application()
 {
 	log_trc("Application::~Application()");
-	Light::Instrumentor::end_session();
+	Instrumentor::end_session();
 }
 
 void Application::game_loop()
@@ -54,8 +43,8 @@ void Application::game_loop()
 	// reveal window
 	m_window->set_visibility(true);
 
-	Light::Instrumentor::end_session();
-	Light::Instrumentor::begin_session("Logs/ProfileResults_GameLoop.json");
+	Instrumentor::end_session();
+	Instrumentor::begin_session("Logs/ProfileResults_GameLoop.json");
 
 	/* game loop */
 	auto delta_timer = DeltaTimer {};
@@ -65,9 +54,10 @@ void Application::game_loop()
 			// update layers
 			lt_profile_scope("game_loop::update");
 
-			for (auto & it : *m_layer_stack) {
+			for (auto &it : *m_layer_stack)
+			{
 				it->on_update(delta_timer.get_delta_time());
-}
+			}
 		}
 
 		{
@@ -75,9 +65,10 @@ void Application::game_loop()
 			lt_profile_scope("game_loop::Render");
 			m_window->get_graphics_context()->get_renderer()->begin_frame();
 
-			for (auto & it : *m_layer_stack) {
+			for (auto &it : *m_layer_stack)
+			{
 				it->on_render();
-}
+			}
 
 			m_window->get_graphics_context()->get_renderer()->end_frame();
 		}
@@ -87,9 +78,10 @@ void Application::game_loop()
 			lt_profile_scope("game_loop::UserInterface");
 			m_window->get_graphics_context()->get_user_interface()->begin();
 
-			for (auto & it : *m_layer_stack) {
+			for (auto &it : *m_layer_stack)
+			{
 				it->on_user_interface_update();
-}
+			}
 
 			m_window->get_graphics_context()->get_user_interface()->end();
 		}
@@ -104,13 +96,13 @@ void Application::game_loop()
 		delta_timer.update();
 	}
 
-	Light::Instrumentor::end_session();
-	Light::Instrumentor::begin_session("Logs/ProfileResults_Termination.json");
+	Instrumentor::end_session();
+	Instrumentor::begin_session("Logs/ProfileResults_Termination.json");
 }
 
 void Application::quit()
 {
-	s_context->m_window->close();
+	/** TODO: fix quitting procedure */
 }
 
 void Application::on_event(const Event &event)
@@ -120,19 +112,20 @@ void Application::on_event(const Event &event)
 	{
 		m_window->on_event(event);
 
-		if (event.get_event_type() == EventType::WindowResized) {
+		if (event.get_event_type() == EventType::WindowResized)
+		{
 			m_window->get_graphics_context()->get_renderer()->on_window_resize(
 			    (const WindowResizedEvent &)event
 			);
-}
+		}
 	}
 
 	// input
 	if (event.has_category(InputEventCategory))
 	{
-		m_input->on_event(event);
+		Input::instance().on_event(event);
 
-		if (!m_input->is_receiving_game_events())
+		if (!Input::instance().is_receiving_game_events())
 		{
 			return;
 		}
@@ -149,13 +142,10 @@ void Application::on_event(const Event &event)
 
 void Application::log_debug_data()
 {
-	// #todo: log more information
-	log_inf("________________________________________");
 	log_inf("Platform::");
 	log_inf("       Platform name: {}", constants::platform_name);
 	log_inf("       Platform identifier: {}", std::to_underlying(constants::platform));
 	log_inf("       CWD: {}", std::filesystem::current_path().generic_string());
-	log_inf("________________________________________");
 }
 
 } // namespace Light
diff --git a/modules/engine/src/debug/instrumentor.cpp b/modules/engine/src/debug/instrumentor.cpp
index c524757..753dae6 100644
--- a/modules/engine/src/debug/instrumentor.cpp
+++ b/modules/engine/src/debug/instrumentor.cpp
@@ -2,23 +2,6 @@
 
 namespace Light {
 
-Instrumentor *Instrumentor::s_context = nullptr;
-
-auto Instrumentor::create() -> Scope<Instrumentor>
-{
-	return make_scope<Instrumentor>(new Instrumentor);
-}
-
-Instrumentor::Instrumentor() 
-{
-	// #todo: maintenance
-	lt_assert(
-	    !s_context,
-	    "An instance of 'Instrumentor' already exists, do not construct this class!"
-	);
-	s_context = this;
-}
-
 void Instrumentor::begin_session_impl(const std::string &outputPath)
 {
 	std::filesystem::create_directory(outputPath.substr(0, outputPath.find_last_of('/') + 1));
@@ -29,9 +12,10 @@ void Instrumentor::begin_session_impl(const std::string &outputPath)
 
 void Instrumentor::end_session_impl()
 {
-	if (m_current_session_count == 0u) {
+	if (m_current_session_count == 0u)
+	{
 		log_wrn("0 profiling for the ended session");
-}
+	}
 
 	m_current_session_count = 0u;
 
@@ -42,11 +26,14 @@ void Instrumentor::end_session_impl()
 
 void Instrumentor::submit_scope_profile_impl(const ScopeProfileResult &profileResult)
 {
-	if (m_current_session_count++ == 0u) {
+	if (m_current_session_count++ == 0u)
+	{
 		m_output_file_stream << "{";
-	} else {
+	}
+	else
+	{
 		m_output_file_stream << ",{";
-}
+	}
 
 	m_output_file_stream << R"("name":")" << profileResult.name << "\",";
 	m_output_file_stream << R"("cat": "scope",)";
@@ -59,7 +46,7 @@ void Instrumentor::submit_scope_profile_impl(const ScopeProfileResult &profileRe
 }
 
 InstrumentorTimer::InstrumentorTimer(const std::string &scopeName)
-    : m_result({ .name=scopeName, .start=0, .duration=0, .threadID=0 })
+    : m_result({ .name = scopeName, .start = 0, .duration = 0, .threadID = 0 })
     , m_start(std::chrono::steady_clock::now())
 {
 }
diff --git a/modules/engine/src/input/input.cpp b/modules/engine/src/input/input.cpp
index b0a72cc..53e1b6c 100644
--- a/modules/engine/src/input/input.cpp
+++ b/modules/engine/src/input/input.cpp
@@ -8,25 +8,9 @@
 
 namespace Light {
 
-Input *Input::s_context = nullptr;
+Input::Input(): m_mouse_position {}, m_mouse_delta {}
 
-auto Input::create() -> Scope<Input>
 {
-	return make_scope(new Input);
-}
-
-Input::Input()
-    : 
-     m_mouse_position {}
-    , m_mouse_delta {}
-     
-{
-	lt_assert(
-	    !s_context,
-	    "Input::Input: an instance of 'Input' already exists, do not construct this class!"
-	);
-	s_context = this;
-
 	restart_input_state();
 }
 
@@ -40,9 +24,10 @@ void Input::receieve_game_events_impl(bool receive, bool toggle /*= false*/)
 	auto prev = m_game_events;
 	m_game_events = toggle ? !m_user_interface_events : receive;
 
-	if (m_game_events != prev) {
+	if (m_game_events != prev)
+	{
 		restart_input_state();
-}
+	}
 }
 
 void Input::restart_input_state()
@@ -71,9 +56,10 @@ void Input::on_event(const Event &inputEvent)
 			m_mouse_position = event.get_position();
 		}
 
-		if (m_user_interface_events) {
+		if (m_user_interface_events)
+		{
 			io.MousePos = ImVec2(event.get_x(), event.get_y());
-}
+		}
 
 		return;
 	}
@@ -81,13 +67,15 @@ void Input::on_event(const Event &inputEvent)
 	{
 		const auto &event = dynamic_cast<const ButtonPressedEvent &>(inputEvent);
 
-		if (m_game_events) {
+		if (m_game_events)
+		{
 			m_mouse_buttons[event.get_button()] = true;
-}
+		}
 
-		if (m_user_interface_events) {
+		if (m_user_interface_events)
+		{
 			io.MouseDown[event.get_button()] = true;
-}
+		}
 
 		return;
 	}
@@ -95,13 +83,15 @@ void Input::on_event(const Event &inputEvent)
 	{
 		const auto &event = dynamic_cast<const ButtonReleasedEvent &>(inputEvent);
 
-		if (m_game_events) {
+		if (m_game_events)
+		{
 			m_mouse_buttons[event.get_button()] = false;
-}
+		}
 
-		if (m_user_interface_events) {
+		if (m_user_interface_events)
+		{
 			io.MouseDown[event.get_button()] = false;
-}
+		}
 
 		return;
 	}
@@ -109,13 +99,15 @@ void Input::on_event(const Event &inputEvent)
 	{
 		const auto &event = dynamic_cast<const WheelScrolledEvent &>(inputEvent);
 
-		if (m_game_events) {
+		if (m_game_events)
+		{
 			m_mouse_wheel_delta = event.get_offset();
-}
+		}
 
-		if (m_user_interface_events) {
+		if (m_user_interface_events)
+		{
 			io.MouseWheel = event.get_offset();
-}
+		}
 
 		return;
 	}
@@ -124,9 +116,10 @@ void Input::on_event(const Event &inputEvent)
 	{
 		const auto &event = dynamic_cast<const KeyPressedEvent &>(inputEvent);
 
-		if (m_game_events) {
+		if (m_game_events)
+		{
 			m_keyboad_keys[event.get_key()] = true;
-}
+		}
 
 		if (m_user_interface_events)
 		{
@@ -141,13 +134,15 @@ void Input::on_event(const Event &inputEvent)
 	{
 		const auto &event = dynamic_cast<const KeyReleasedEvent &>(inputEvent);
 
-		if (m_game_events) {
+		if (m_game_events)
+		{
 			m_keyboad_keys[event.get_key()] = false;
-}
+		}
 
-		if (m_user_interface_events) {
+		if (m_user_interface_events)
+		{
 			io.KeysDown[event.get_key()] = false;
-}
+		}
 
 		return;
 	}
diff --git a/modules/engine/src/layer/layer_stack.cpp b/modules/engine/src/layer/layer_stack.cpp
index fd58804..a94d890 100644
--- a/modules/engine/src/layer/layer_stack.cpp
+++ b/modules/engine/src/layer/layer_stack.cpp
@@ -7,27 +7,12 @@
 
 namespace Light {
 
-LayerStack *LayerStack::s_context = nullptr;
-
-auto LayerStack::create() -> Scope<LayerStack>
-{
-	return make_scope<LayerStack>(new LayerStack());
-}
-
-LayerStack::LayerStack() 
-{
-	lt_assert(
-	    !s_context,
-	    "An instance of 'LayerStack' already exists, do not construct this class!"
-	) s_context
-	    = this;
-}
-
 LayerStack::~LayerStack()
 {
-	for (auto *layer : m_layers) {
+	for (auto *layer : m_layers)
+	{
 		delete layer;
-}
+	}
 }
 
 void LayerStack::attach_layer_impl(Layer *layer)
diff --git a/modules/engine/src/utils/resource_manager.cpp b/modules/engine/src/utils/resource_manager.cpp
index 6172dfb..ab33375 100644
--- a/modules/engine/src/utils/resource_manager.cpp
+++ b/modules/engine/src/utils/resource_manager.cpp
@@ -6,19 +6,6 @@
 
 namespace Light {
 
-ResourceManager *ResourceManager::s_context = nullptr;
-
-auto ResourceManager::create() -> Scope<ResourceManager>
-{
-	return make_scope(new ResourceManager());
-}
-
-ResourceManager::ResourceManager() 
-{
-	lt_assert(!s_context, "Repeated singleton construction");
-	s_context = this;
-}
-
 void ResourceManager::load_shader_impl(
     const std::string &name,
     const std::string &vertexPath,
@@ -26,7 +13,6 @@ void ResourceManager::load_shader_impl(
 )
 {
 	// check
-	lt_assert(s_context, "Uninitliazed singleton");
 	lt_assert(!vertexPath.empty(), "Empty 'vertexPath'");
 	lt_assert(!pixelPath.empty(), "Empty 'pixelPath'");
 
@@ -54,8 +40,6 @@ void ResourceManager::load_texture_impl(
     unsigned int desiredComponents /* = 4u */
 )
 {
-	lt_assert(s_context, "Uninitliazed singleton");
-
 	// load file
 	auto imgFile = FileManager::read_image_file(path, desiredComponents);
 
diff --git a/modules/engine/src/utils/serializer.cpp b/modules/engine/src/utils/serializer.cpp
index 0a50ac8..a5c9c2f 100644
--- a/modules/engine/src/utils/serializer.cpp
+++ b/modules/engine/src/utils/serializer.cpp
@@ -19,9 +19,10 @@ struct convert<glm::vec3>
 
 	static auto decode(const Node &node, glm::vec3 &rhs) -> bool
 	{
-		if (!node.IsSequence() || node.size() != 3) {
+		if (!node.IsSequence() || node.size() != 3)
+		{
 			return false;
-}
+		}
 
 		rhs.x = node[0].as<float>();
 		rhs.y = node[1].as<float>();
@@ -45,9 +46,10 @@ struct convert<glm::vec4>
 
 	static auto decode(const Node &node, glm::vec4 &rhs) -> bool
 	{
-		if (!node.IsSequence() || node.size() != 4) {
+		if (!node.IsSequence() || node.size() != 4)
+		{
 			return false;
-}
+		}
 
 		rhs.x = node[0].as<float>();
 		rhs.y = node[1].as<float>();
@@ -60,14 +62,14 @@ struct convert<glm::vec4>
 
 namespace Light {
 
-static auto operator<<(YAML::Emitter &out, const glm::vec3 &v) -> YAML::Emitter &
+auto operator<<(YAML::Emitter &out, const glm::vec3 &v) -> YAML::Emitter &
 {
 	out << YAML::Flow;
 	out << YAML::BeginSeq << v.x << v.y << v.z << YAML::EndSeq;
 	return out;
 }
 
-static auto operator<<(YAML::Emitter &out, const glm::vec4 &v) -> YAML::Emitter &
+auto operator<<(YAML::Emitter &out, const glm::vec4 &v) -> YAML::Emitter &
 {
 	out << YAML::Flow;
 	out << YAML::BeginSeq << v.x << v.y << v.z << v.w << YAML::EndSeq;