diff --git a/Redcraft.FocusIME/Source/Private/Defines.h b/Redcraft.FocusIME/Source/Private/Defines.h
new file mode 100644
index 0000000..77aa6a5
--- /dev/null
+++ b/Redcraft.FocusIME/Source/Private/Defines.h
@@ -0,0 +1,129 @@
+#pragma once
+
+// Platform information macro
+
+#ifndef PLATFORM_NAME
+#	error "PLATFORM_NAME must be defined."
+#endif
+
+#ifndef PLATFORM_WINDOWS
+#	define PLATFORM_WINDOWS 0
+#endif
+
+#ifndef PLATFORM_LINUX
+#	define PLATFORM_LINUX 0
+#endif
+
+#ifndef PLATFORM_UNKNOWN
+#	define PLATFORM_UNKNOWN 0
+#endif
+
+// Build information macro
+
+#ifndef BUILD_TYPE
+#	error "BUILD_TYPE must be defined."
+#endif
+
+#ifndef BUILD_DEBUG
+#	define BUILD_DEBUG 0
+#endif
+
+#ifndef BUILD_DEVELOPMENT
+#	define BUILD_DEVELOPMENT 0
+#endif
+
+#ifndef BUILD_RELEASE
+#	define BUILD_RELEASE 0
+#endif
+
+#ifndef BUILD_UNKNOWN
+#	define BUILD_UNKNOWN 0
+#endif
+
+// Compiler information macro
+
+#ifndef PLATFORM_COMPILER_NAME
+#	error "COMPILER_NAME must be defined."
+#endif
+
+#ifndef PLATFORM_COMPILER_MSVC
+#	define PLATFORM_COMPILER_MSVC 0
+#endif
+
+#ifndef PLATFORM_COMPILER_CLANG
+#	define PLATFORM_COMPILER_CLANG 0
+#endif
+
+#ifndef PLATFORM_COMPILER_GCC
+#	define PLATFORM_COMPILER_GCC 0
+#endif
+
+#ifndef PLATFORM_COMPILER_UNKNOWN
+#	define PLATFORM_COMPILER_UNKNOWN 0
+#endif
+
+// Architecture information macro
+
+#ifndef PLATFORM_CPU_X86_FAMILY
+#	if (defined(_M_IX86) || defined(__i386__) || defined(_M_X64) || defined(__amd64__) || defined(__x86_64__))
+#		define PLATFORM_CPU_X86_FAMILY 1
+#	else
+#		define PLATFORM_CPU_X86_FAMILY 0
+#	endif
+#endif
+
+#ifndef PLATFORM_CPU_ARM_FAMILY
+#	if (defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || defined(_M_ARM64))
+#		define PLATFORM_CPU_ARM_FAMILY 1
+#	else
+#		define PLATFORM_CPU_ARM_FAMILY 0
+#	endif
+#endif
+
+#ifndef PLATFORM_CPU_UNKNOWN_FAMILY
+#	define PLATFORM_CPU_UNKNOWN_FAMILY (!(PLATFORM_CPU_X86_FAMILY || PLATFORM_CPU_ARM_FAMILY))
+#endif
+
+// CPU bits information macro
+
+#ifndef PLATFORM_CPU_BITS
+#	if (defined(_M_X64) || defined(__amd64__) || defined(__x86_64__) || defined(__aarch64__) || defined(_M_ARM64))
+#		define PLATFORM_CPU_BITS 64
+#	elif (defined(_M_IX86) || defined(__i386__) || defined(__arm__) || defined(_M_ARM))
+#		define PLATFORM_CPU_BITS 32
+#	else
+#		define PLATFORM_CPU_BITS 0
+#	endif
+#endif
+
+// Endian information macro
+
+#if !defined(PLATFORM_LITTLE_ENDIAN) && !defined(PLATFORM_BIG_ENDIAN)
+#	if PLATFORM_COMPILER_MSVC
+#		define PLATFORM_LITTLE_ENDIAN 1
+#		define PLATFORM_BIG_ENDIAN    0
+#	elif defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_BIG_ENDIAN__)
+#		if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#			define PLATFORM_LITTLE_ENDIAN 1
+#			define PLATFORM_BIG_ENDIAN    0
+#		elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#			define PLATFORM_LITTLE_ENDIAN 0
+#			define PLATFORM_BIG_ENDIAN    1
+#		else
+#			define PLATFORM_LITTLE_ENDIAN 0
+#			define PLATFORM_BIG_ENDIAN    0
+#		endif
+#	endif
+#endif
+
+#ifndef PLATFORM_LITTLE_ENDIAN
+#	define PLATFORM_LITTLE_ENDIAN 0
+#endif
+
+#ifndef PLATFORM_BIG_ENDIAN
+#	define PLATFORM_BIG_ENDIAN    0
+#endif
+
+#ifndef PLATFORM_MIXED_ENDIAN
+#	define PLATFORM_MIXED_ENDIAN  (!(PLATFORM_LITTLE_ENDIAN || PLATFORM_BIG_ENDIAN))
+#endif
diff --git a/Redcraft.FocusIME/Source/Private/Main.cpp b/Redcraft.FocusIME/Source/Private/Main.cpp
index c44d85e..b08604e 100644
--- a/Redcraft.FocusIME/Source/Private/Main.cpp
+++ b/Redcraft.FocusIME/Source/Private/Main.cpp
@@ -1,28 +1,104 @@
-#include <windows.h>
+#include "Defines.h"
+
+#include <windows.h>
 #include <iostream>
+#include <fstream>
 #include <thread>
 #include <chrono>
+#include <string>
+#include <filesystem>
+#include <ctime>
+#include <iomanip>
+#include <mutex>
 
 #pragma warning(disable: 4996)
 
 // ReSharper disable CppDeprecatedEntity
 // ReSharper disable CppClangTidyCertErr33C
 
+std::ofstream GLogFile;
+
+void PrintLog(const std::string& Text)
+{
+	const auto Now  = std::chrono::system_clock::now();
+	const auto Time = std::chrono::system_clock::to_time_t(Now);
+
+	const long long Milliseconds = (std::chrono::duration_cast<std::chrono::milliseconds>(Now.time_since_epoch()) % 1000).count();
+
+	static std::mutex Mutex; std::lock_guard Lock(Mutex);
+
+	const std::tm* LocalTime = std::localtime(&Time); // NOLINT(concurrency-mt-unsafe)
+
+	char Buffer[] = "[2025-06-21 20:05:04.305]: ";
+
+	std::strftime(&Buffer[1], 20, "%Y-%m-%d %H:%M:%S", LocalTime);
+
+	Buffer[20] = '.';
+
+	constexpr char Digits[] = "0123456789";
+
+	Buffer[21] = Digits[Milliseconds / 100 % 10];
+	Buffer[22] = Digits[Milliseconds /  10 % 10];
+	Buffer[23] = Digits[Milliseconds /   1 % 10];
+
+	GLogFile << Buffer << Text << std::endl;
+}
+
 int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
 {
 	using namespace std::chrono_literals;
 
-	AllocConsole();
+	const HANDLE Mutex = CreateMutex(nullptr, TRUE, "FocusIME_SingleInstance_Mutex");
 
-	freopen("CONOUT$", "w", stdout);
+	if (Mutex == nullptr)
+	{
+		MessageBox(nullptr, "Failed to create mutex.", "FocusIME", MB_OK | MB_ICONERROR);
 
-	SetConsoleTitle("FocusIME");
+		return 1;
+	}
 
-	std::cout << "Hello, FocusIME!" << std::endl;
+	if (GetLastError() == ERROR_ALREADY_EXISTS)
+	{
+		MessageBox(nullptr, "FocusIME is already running.", "FocusIME", MB_OK | MB_ICONINFORMATION);
 
-	std::this_thread::sleep_for(3s);
+		CloseHandle(Mutex);
 
-	FreeConsole();
+		return 0;
+	}
+
+	GLogFile.open("Log.txt", std::ios::out | std::ios::app);
+
+	if (!GLogFile.is_open())
+	{
+		MessageBox(nullptr, "Failed to open log file.", "FocusIME", MB_OK | MB_ICONERROR);
+
+		CloseHandle(Mutex);
+
+		return 1;
+	}
+
+	PrintLog("FocusIME started successfully");
+
+	MSG Message = { };
+
+	while (true)
+	{
+		BOOL bResult = GetMessage(&Message, nullptr, 0, 0);
+
+		if (bResult > 0)
+		{
+			TranslateMessage(&Message);
+			DispatchMessage (&Message);
+		}
+
+		else break;
+	}
+
+	PrintLog("FocusIME is shutting down...");
+
+	GLogFile.close();
+
+	CloseHandle(Mutex);
 
 	return 0;
 }