diff --git a/app.js b/app.js
index d95cc75..196ceeb 100644
--- a/app.js
+++ b/app.js
@@ -11,8 +11,10 @@ const windowName = require('get-window-by-name');
 const terminalUtil = require('./terminalUtil');
 const osUtil = require('./osUtil');
 const appInfo = require('./appInfo');
+const executeUtil = require("./executeUtil");
 const { DownloaderHelper } = require('node-downloader-helper');
 
+let patcherLoc = undefined;
 let tempOsuPath;
 let osuWindowInfo;
 let isIngame;
@@ -36,6 +38,13 @@ const run = () => {
           if (!osuLoaded) {
             osuLoaded = true;
             //TODO: do patch
+            setTimeout(() => {
+              console.log("yes");
+              if (patcherLoc) {
+                console.log("running " + patcherLoc + " in dir " + path.dirname(patcherLoc));
+                executeUtil.runFileDetached(path.dirname(patcherLoc), patcherLoc);
+              }
+            }, 5000);
           }
           const windowTitle = firstInstance.processTitle;
           let rpcOsuVersion = "";
@@ -215,8 +224,13 @@ const run = () => {
     app.on('window-all-closed', () => {
       app.quit()
     })
-    ipcMain.handle('launch', async () => {
+    ipcMain.handle('launch', async (e, opts) => {
+      console.log(opts);
+      const patch = "patch" in opts && opts.patch;
       const osuFolder = await config.get("osuPath");
+      if (patch) patcherLoc = path.join(osuFolder, "EZPPLauncher", "patcher.exe");
+      else patcherLoc = undefined;
+
       await osuUtil.updateOsuCfg(path.join(osuFolder, "osu!.cfg"));
       const osuConfig = await osuUtil.getLatestConfig(tempOsuPath);
       const username = await config.get('username');
@@ -240,6 +254,7 @@ const run = () => {
         if (!mainWindow.isVisible()) mainWindow.show();
         setTimeout(async () => {
           isIngame = false;
+          osuLoaded = false;
           await osuUtil.replaceUI(osuFolder, false);
           await doUpdateCheck(mainWindow);
           mainWindow.closable = true;
diff --git a/executeUtil.js b/executeUtil.js
index cb5d5ae..adb4e6b 100644
--- a/executeUtil.js
+++ b/executeUtil.js
@@ -4,11 +4,12 @@ module.exports = {
         childProcess.execFile(file, args, {
             cwd: folder
         }, (_err, _stdout, _stderr) => {
-            onExit();
+            if (onExit)
+                onExit();
         });
     },
     runFileDetached: (folder, file, args) => {
-        const subprocess = childProcess.spawn(file + " " + args, {
+        const subprocess = childProcess.spawn(file + (args ? " " + args : ''), {
             cwd: folder,
             detached: true,
             stdio: 'ignore'
diff --git a/html/index.html b/html/index.html
index 2d0126f..8087f04 100644
--- a/html/index.html
+++ b/html/index.html
@@ -64,8 +64,8 @@
                                     </div>
                                     <div class="launch-button-section">
                                         <button class="btn btn-lg btn-launch btn-accent" id="launch-btn" disabled>Launch</button>
-                                        <div class="patch-checkbox" style="display: none;">
-                                            <input type="checkbox" id="enablePatching" disabled />
+                                        <div class="patch-checkbox">
+                                            <input type="checkbox" id="enablePatching" checked/>
                                             <label for="enablePatching" style="display: initial;">enable
                                                 Patching</label>
                                         </div>
diff --git a/osuUtil.js b/osuUtil.js
index 8171ab5..3df125a 100644
--- a/osuUtil.js
+++ b/osuUtil.js
@@ -11,6 +11,14 @@ const checkUpdateURL = "https://osu.ppy.sh/web/check-updates.php?action=check&st
 const customUIDLLPath = "https://ez-pp.farm/assets/ezpp!ui.dll";
 const customUIDLLHash = "https://ez-pp.farm/assets/ezpp!ui.md5";
 const customUIDLLName = "ezpp!ui.dll";
+
+const patcherHook = "https://ez-pp.farm/assets/patch.hook.dll";
+const patcherHookHash = "https://ez-pp.farm/assets/patch.hook.md5";
+const patcherHookName = "patch.hook.dll";
+const patcherExe = "https://ez-pp.farm/assets/patcher.exe";
+const patcherExeHash = "https://ez-pp.farm/assets/patcher.md5"
+const patcherExeName = "patcher.exe";
+
 const ignoredOsuEntities = [
   'osu!auth.dll',
 ]
@@ -86,6 +94,11 @@ async function getEZPPUIMD5() {
   return releaseData.data;
 }
 
+async function getMD5Hash(url) {
+  const releaseData = await axios.get(url, {});
+  return releaseData.data;
+}
+
 async function filesThatNeedUpdate(osuPath, updateFiles) {
   const filesToDownload = [];
   for (const updatedFile of updateFiles) {
@@ -122,11 +135,56 @@ async function filesThatNeedUpdate(osuPath, updateFiles) {
   }
 
   const ezppUI = path.join(osuPath, "EZPPLauncher", customUIDLLName);
+  const hook = path.join(osuPath, "EZPPLauncher", patcherHookName);
+  const patcher = path.join(osuPath, "EZPPLauncher", patcherExeName);
+
+  if (await fu.existsAsync(hook)) {
+    const latestHookMd5Hash = (await getMD5Hash(patcherHookHash)).toLowerCase().trim();
+    const binaryHookContents = await fs.promises.readFile(hook);
+    const existingHookMD5 = crypto.createHash("md5").update(binaryHookContents).digest("hex").toLowerCase().trim();
+    if (existingHookMD5 != latestHookMd5Hash) {
+      filesToDownload.push({
+        folder: "EZPPLauncher",
+        fileName: patcherHookName,
+        fileURL: patcherHook
+      });
+      console.log("patcher has wrong hashsum (" + existingHookMD5 + " / " + latestHookMd5Hash + ")");
+    }
+  } else {
+    filesToDownload.push({
+      folder: "EZPPLauncher",
+      fileName: patcherHookName,
+      fileURL: patcherHook
+    });
+    console.log("patcher does not exist");
+  }
+
+  if (await fu.existsAsync(patcher)) {
+    const latestPatchMd5Hash = (await getMD5Hash(patcherExeHash)).toLowerCase().trim();
+    const binaryPatchContents = await fs.promises.readFile(patcher);
+    const existingPatchMD5 = crypto.createHash("md5").update(binaryPatchContents).digest("hex").toLowerCase().trim();
+    if (existingPatchMD5 != latestPatchMd5Hash) {
+      filesToDownload.push({
+        folder: "EZPPLauncher",
+        fileName: patcherExeName,
+        fileURL: patcherExe
+      });
+      console.log("patcher has wrong hashsum (" + existingPatchMD5 + " / " + latestPatchMd5Hash + ")")
+    }
+  } else {
+    filesToDownload.push({
+      folder: "EZPPLauncher",
+      fileName: patcherExeName,
+      fileURL: patcherExe
+    });
+    console.log("patcher does not exist");
+  }
+
   if (await fu.existsAsync(ezppUI)) {
-    const latestMd5Hash = await getEZPPUIMD5();
+    const latestUIMd5Hash = (await getMD5Hash(customUIDLLHash)).toLowerCase().trim();
     const binaryUIContents = await fs.promises.readFile(ezppUI);
-    const existingUIMD5 = crypto.createHash("md5").update(binaryUIContents).digest("hex");
-    if (existingUIMD5 != latestMd5Hash) {
+    const existingUIMD5 = crypto.createHash("md5").update(binaryUIContents).digest("hex").toLowerCase().trim();
+    if (existingUIMD5 != latestUIMd5Hash) {
       filesToDownload.push({
         folder: "EZPPLauncher",
         fileName: "ezpp!ui.dll",
@@ -141,6 +199,8 @@ async function filesThatNeedUpdate(osuPath, updateFiles) {
     })
   }
 
+  console.log(JSON.stringify(filesToDownload, null, 2))
+
   return filesToDownload;
 }
 
@@ -149,16 +209,18 @@ async function downloadUpdateFiles(osuPath, filesToUpdate) {
   let completedIndex = 0;
   filesToUpdate.forEach(async (fileToUpdate) => {
 
+    let tempPath = osuPath;
+
     if ("folder" in fileToUpdate) {
-      osuPath = path.join(osuPath, fileToUpdate.folder);
-      if (!(await fu.existsAsync(osuPath))) await fs.promises.mkdir(osuPath);
+      tempPath = path.join(tempPath, fileToUpdate.folder);
+      if (!(await fu.existsAsync(tempPath))) await fs.promises.mkdir(tempPath);
     }
 
-    const filePath = path.join(osuPath, fileToUpdate.fileName);
+    const filePath = path.join(tempPath, fileToUpdate.fileName);
     if (await fu.existsAsync(filePath))
       await fs.promises.rm(filePath);
 
-    const fileDownload = new DownloaderHelper(fileToUpdate.fileURL, osuPath, {
+    const fileDownload = new DownloaderHelper(fileToUpdate.fileURL, tempPath, {
       fileName: fileToUpdate.fileName,
       override: true,
     });
diff --git a/preload/preload.js b/preload/preload.js
index f7f939d..0c9246b 100644
--- a/preload/preload.js
+++ b/preload/preload.js
@@ -48,7 +48,7 @@ window.addEventListener('DOMContentLoaded', () => {
       case "up-to-date":
         $("#launch-btn").attr('disabled', true);
         $('#launch-btn').html('Launching...');
-        const result = await ipcRenderer.invoke("launch");
+        const result = await ipcRenderer.invoke("launch", { patch: true });
         if (!result) {
           Swal.fire({
             title: 'Uh oh!',