diff --git a/Assets/RothenburgAR/Scripts/Updater/UpdaterBehaviour.cs b/Assets/RothenburgAR/Scripts/Updater/UpdaterBehaviour.cs
index efe60a5..58c8325 100644
--- a/Assets/RothenburgAR/Scripts/Updater/UpdaterBehaviour.cs
+++ b/Assets/RothenburgAR/Scripts/Updater/UpdaterBehaviour.cs
@@ -6,7 +6,8 @@ using System;
 using Newtonsoft.Json;
 using RothenburgAR.Common;
 using System.IO;
-using TMPro;
+using System.IO.Compression;
+using System.Security.Cryptography;
 
 namespace RothenburgAR.Updater
 {
@@ -24,6 +25,8 @@ namespace RothenburgAR.Updater
         private List<HttpHandler> httpHandlers = new List<HttpHandler>();
         private LogFileHandler logFileHandler;
 
+        private readonly List<string> downloadingMedia = new List<string>();
+
         void Start()
         {
 #if !UNITY_EDITOR
@@ -74,7 +77,7 @@ namespace RothenburgAR.Updater
 
                 var answer = VersionAnswer;
 
-                if (answer.Data.TrueForAll(d => d.Meta.Status == VersionStatus.ok && d.Tracker.Status == VersionStatus.ok))
+                if (VersionAnswer.Data.TrueForAll(d => d.Meta.Status == VersionStatus.ok && d.Tracker.Status == VersionStatus.ok))
                 {
                     // no updates required, continue to app
                     LoadMainScene();
@@ -116,7 +119,6 @@ namespace RothenburgAR.Updater
             };
 
             result = result.Substring(0, result.Length - 1) + "}";
-            return "{}";
             return result;
         }
 
@@ -141,6 +143,7 @@ namespace RothenburgAR.Updater
 
             UpdateConfirmationDialog.SetActive(false);
             UpdateFailedDialog.SetActive(false);
+            this.downloadingMedia.Clear();
 
             if (VersionAnswer == null)
             {
@@ -233,19 +236,22 @@ namespace RothenburgAR.Updater
 
             foreach (var mediaId in mediaIDs)
             {
-                //System.Security.Cryptography.MD5CryptoServiceProvider
-                //System.Security.Cryptography.SHA1CryptoServiceProvider
-                //System.Security.Cryptography.SHA256
+                if (downloadingMedia.Contains(mediaId)) continue;
+                downloadingMedia.Add(mediaId);
 
                 var path = PathHelper.CombinePaths(PathHelper.MediaPath, mediaId);
-                var filepath = Path.Combine(path, "media.zip");
+                var filepath = Path.Combine(path, mediaId + ".med");
 
                 // create dir if nonexistent
                 if (!Directory.Exists(path)) Directory.CreateDirectory(path);
 
+                //System.Security.Cryptography.SHA1CryptoServiceProvider
+                //System.Security.Cryptography.SHA256
+                var eTag = GenerateETag(filepath);
+
                 var url = ApiInfo.FileEndpoint.Replace("{id}", mediaId);
                 var http = new HttpRequest(url, HttpVerb.GET)
-                    .WithHeader("ETag", "")
+                    .WithHeader("If-None-Match", eTag)
                     .Send();
 
                 httpHandlers.Add(http);
@@ -257,16 +263,74 @@ namespace RothenburgAR.Updater
                         return;
                     }
 
-                    var x = http;
+                    // do nothing if unchanged
+                    if (http.Request.responseCode == 304) return;
 
-                    //TODO unzip
-                    var type = http.Request.GetResponseHeader("Content-Type");
+                    // gzipped files are un-gzipped automagically
                     File.WriteAllBytes(filepath, http.Download.data);
+
+                    var subfilesHeader = http.Request.GetResponseHeader("subfiles");
+                    if (subfilesHeader != null)
+                    {
+                        string[] separator = new string[1] { ";;" };
+                        var subfiles = subfilesHeader.Split(separator, StringSplitOptions.RemoveEmptyEntries);
+                        foreach (var subfile in subfiles)
+                        {
+                            UpdateSubfile(path, mediaId, subfile);
+                        }
+                    }
+
                     Debug.Log(string.Format("{1}-DONE with {0}", url, Time.realtimeSinceStartup));
                 };
             }
         }
 
+        private string GenerateETag(string filepath)
+        {
+            string eTag = "";
+            if (File.Exists(filepath))
+            {
+                var bytes = File.ReadAllBytes(filepath);
+                SHA256Managed hasher = new SHA256Managed();
+                byte[] hash = hasher.ComputeHash(bytes);
+                eTag = "sha256-";
+                foreach (byte x in hash)
+                {
+                    eTag += String.Format("{0:x2}", x);
+                }
+            }
+            return eTag;
+        }
+
+        private void UpdateSubfile(string path, string mediaId, string subfile)
+        {
+            var filepath = Path.Combine(path, subfile);
+            var eTag = GenerateETag(filepath);
+
+            var url = ApiInfo.FileEndpoint.Replace("{id}", mediaId) + "/" + subfile;
+            var http = new HttpRequest(url, HttpVerb.GET)
+                .WithHeader("If-None-Match", eTag)
+                .Send();
+
+            httpHandlers.Add(http);
+
+            http.Operation.completed += ar =>
+            {
+                if (CheckNetworkErrors(http))
+                {
+                    return;
+                }
+
+                // do nothing if unchanged
+                if (http.Request.responseCode == 304) return;
+
+                // gzipped files are un-gzipped automagically
+                File.WriteAllBytes(filepath, http.Download.data);
+
+                Debug.Log(string.Format("{1}-DONE with {0}", url, Time.realtimeSinceStartup));
+            };
+        }
+
         private bool CheckNetworkErrors(HttpHandler http)
         {
             if (http.Request.isNetworkError || http.Request.isHttpError)