This is a unity3d test...

![enter image description here][1]

To get the zip file back download the image as file and recode it using this code

        static void Main(string[] args)
        {
             BmpToFile(@"c:\your\download\LA3s5.png", @"code.zip");
        }

        private static void BmpToFile(string src, string dst)
        {
            var file = File.OpenWrite(dst);
           
            var bitmap = new Bitmap(src);

            var data = bitmap.LockBits(
                new Rectangle(0, 0, bitmap.Width, bitmap.Height), 
                ImageLockMode.WriteOnly, 
                PixelFormat.Format8bppIndexed);

            var line = new byte[data.Stride];
            for(var lineCount=0; lineCount< data.Height; lineCount++)
            {
                Marshal.Copy(data.Scan0 + lineCount* data.Stride, 
                    line, 0, data.Stride);
                file.Write(line,0, line.Length);
            }
            bitmap.UnlockBits(data);
            file.Close();
        }


  [1]: https://i.sstatic.net/HmLfp.png