diff --git a/Assets/Cryville/Crtr/Network.meta b/Assets/Cryville/Crtr/Network.meta
new file mode 100644
index 0000000..629ded7
--- /dev/null
+++ b/Assets/Cryville/Crtr/Network.meta
@@ -0,0 +1,8 @@
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diff --git a/Assets/Cryville/Crtr/Network/UpdateChecker.cs b/Assets/Cryville/Crtr/Network/UpdateChecker.cs
new file mode 100644
index 0000000..56927bb
--- /dev/null
+++ b/Assets/Cryville/Crtr/Network/UpdateChecker.cs
@@ -0,0 +1,105 @@
+using Cryville.Common.Network;
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using UnityEngine;
+using Logger = Cryville.Common.Logging.Logger;
+using ThreadPriority = System.Threading.ThreadPriority;
+
+namespace Cryville.Crtr.Network {
+	public class UpdateChecker : MonoBehaviour {
+		string _currentVersion;
+		void Start() {
+			_currentVersion = Application.version;
+			new Thread(CheckVersion) { IsBackground = true, Priority = ThreadPriority.BelowNormal }.Start();
+		}
+		static readonly Uri BaseUri = new Uri("https://www.cryville.world/api/crtr/index");
+		List<VersionInfo> _versions;
+		public void CheckVersion() {
+			try {
+				var client = new HttpsClient(BaseUri);
+				client.Connect();
+				var response = client.Request("GET", new Uri(BaseUri, "versions"));
+				var data = Encoding.UTF8.GetString(response.MessageBody.ReadToEnd());
+				_versions = JsonConvert.DeserializeObject<List<VersionInfo>>(data, Game.GlobalJsonSerializerSettings);
+			}
+			catch (Exception ex) {
+				Logger.Log("main", 4, "Network", "An error occurred while checking for update: {0}", ex);
+				Dialog.Show(null, "Failed to check for update.");
+				return;
+			}
+			var availableVersions = (from v in _versions where v.platforms.ContainsKey(PlatformConfig.Name) select v).ToArray();
+			var versionIndex = new Dictionary<string, int>(availableVersions.Length);
+			for (int i = 0; i < availableVersions.Length; i++) versionIndex.Add(availableVersions[i].name, i);
+			var currentVersion = (from v in availableVersions where v.name == _currentVersion select v).SingleOrDefault();
+			var latestVersion = availableVersions.Last();
+			if (currentVersion == null) {
+				Dialog.Show(null, string.Format("You are playing an unknown version of Cosmo Resona: {0}\nThe latest version is: {1}", _currentVersion, latestVersion.name));
+				return;
+			}
+			if (latestVersion.name != _currentVersion) {
+				var latestResources = latestVersion.platforms[PlatformConfig.Name].resources;
+				VersionResourceInfo fullPackage = null;
+				if (latestResources != null) {
+					fullPackage = (from r in latestResources where r.upstream == null select r).SingleOrDefault();
+				}
+				if (fullPackage == null) {
+					Dialog.Show(null, string.Format("A new version is present: {0}\nUpdate is not available.", latestVersion.name));
+					return;
+				}
+				long totalDiffSize = 0;
+				int searchIndex = versionIndex[latestVersion.name], targetIndex = versionIndex[currentVersion.name];
+				while (searchIndex != targetIndex) {
+					var searchVersion = availableVersions[searchIndex];
+					VersionResourceInfo matchedUpstream = null;
+					var resources = searchVersion.platforms[PlatformConfig.Name].resources;
+					if (resources == null) {
+						totalDiffSize = 0;
+						break;
+					}
+					foreach (var r in resources) {
+						if (r.upstream == null) continue;
+						var upstreamIndex = versionIndex[r.upstream];
+						if (upstreamIndex >= targetIndex && upstreamIndex < searchIndex) {
+							matchedUpstream = r;
+							searchIndex = upstreamIndex;
+						}
+					}
+					if (matchedUpstream != null) {
+						totalDiffSize += matchedUpstream.size;
+					}
+					else {
+						totalDiffSize = 0;
+						break;
+					}
+				}
+				if (totalDiffSize == 0 || totalDiffSize >= fullPackage.size) {
+					Dialog.ShowAndWait(string.Format("A new version is available: {0}\nYou have to download the full package.\nOpen the download link now?", latestVersion.name), "Yes", "No");
+				}
+				else {
+					Dialog.ShowAndWait(string.Format("A new version is available: {0}\nDo you want to update?", latestVersion.name), "Yes", "No");
+				}
+			}
+		}
+		class VersionInfo {
+			[JsonRequired]
+			public string name;
+			public string type;
+			public Dictionary<string, PlatformVersionInfo> platforms;
+		}
+		class PlatformVersionInfo {
+			public List<VersionResourceInfo> resources;
+		}
+		class VersionResourceInfo {
+			public bool external;
+			public string upstream;
+			[JsonRequired]
+			public string url;
+			[JsonRequired]
+			public long size;
+		}
+	}
+}
diff --git a/Assets/Cryville/Crtr/Network/UpdateChecker.cs.meta b/Assets/Cryville/Crtr/Network/UpdateChecker.cs.meta
new file mode 100644
index 0000000..2c69124
--- /dev/null
+++ b/Assets/Cryville/Crtr/Network/UpdateChecker.cs.meta
@@ -0,0 +1,11 @@
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