[assembly:CLSCompliant(true)]
namespace ColorConsole
{
    public sealed class HelloWorld
    {
        private HelloWorld() { }

        public static void Main()
        {
            const UInt32 STD_OUTPUT_HANDLE = unchecked((UInt32)(-11));
            IntPtr consoleHandle = NativeMethods.GetStdHandle(STD_OUTPUT_HANDLE);

            string s = "Hello World!";

            for (int i = 0; i < s.Length; i++)
            {
                NativeMethods.SetConsoleTextAttribute(consoleHandle, (ushort)(i + 1));
                Console.Write(s[i]);
            }

            Console.ReadLine();
        }
    }

    class NativeMethods
    {
        private NativeMethods() { }

        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern IntPtr GetStdHandle(UInt32 type);

        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.U1)]
        public static extern bool SetConsoleTextAttribute(IntPtr consoleHandle, ushort attributes);  
    }
}