diff --git a/tests/launcher_api_test.py b/tests/launcher_api_test.py
index 6756647..f361676 100644
--- a/tests/launcher_api_test.py
+++ b/tests/launcher_api_test.py
@@ -1,38 +1,47 @@
 import unittest
 import asyncio
 import worthless
-from worthless.classes import launcher
-client = worthless.Launcher()
+from worthless.classes import launcher, installer
+game_launcher = worthless.Launcher()
+game_installer = worthless.Installer()
 
 
 class LauncherOverseasTest(unittest.TestCase):
     def test_get_version_info(self):
-        version_info = asyncio.run(client.get_version_info())
-        print("get_version_info test.")
-        print("get_version_info: ", version_info)
-        self.assertIsInstance(version_info, dict)
+        version_info = asyncio.run(game_launcher.get_resource_info())
+        print("get_resource_info test.")
+        print("get_resource_info: ", version_info)
+        print("raw: ", version_info.raw)
+        self.assertIsInstance(version_info, installer.Resource)
 
     def test_get_launcher_info(self):
-        launcher_info = asyncio.run(client.get_launcher_info())
+        launcher_info = asyncio.run(game_launcher.get_launcher_info())
         print("get_launcher_info test.")
         print("get_launcher_info: ", launcher_info)
         print("raw: ", launcher_info.raw)
         self.assertIsInstance(launcher_info, launcher.Info)
 
     def test_get_launcher_full_info(self):
-        launcher_info = asyncio.run(client.get_launcher_full_info())
+        launcher_info = asyncio.run(game_launcher.get_launcher_full_info())
         print("get_launcher_full_info test.")
         print("get_launcher_full_info: ", launcher_info)
         print("raw: ", launcher_info.raw)
         self.assertIsInstance(launcher_info, launcher.Info)
 
     def test_get_launcher_background_url(self):
-        bg_url = asyncio.run(client.get_launcher_background_url())
+        bg_url = asyncio.run(game_launcher.get_launcher_background_url())
         print("get_launcher_background_url test.")
         print("get_launcher_background_url: ", bg_url)
         self.assertIsInstance(bg_url, str)
         self.assertTrue(bg_url)
 
+    def test_get_installer_diff(self):
+        game_diff = asyncio.run(game_installer.get_game_diff_archive("2.4.0"))
+        print("get_game_diff_archive test.")
+        print("get_game_diff_archive: ", game_diff)
+        print("raw: ", game_diff.raw)
+        self.assertIsInstance(game_diff, installer.Diff)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/worthless/__init__.py b/worthless/__init__.py
index 28ad165..583ae8d 100644
--- a/worthless/__init__.py
+++ b/worthless/__init__.py
@@ -1,3 +1,4 @@
-from worthless import launcher
+from worthless import launcher, installer
 
 Launcher = launcher.Launcher
+Installer = installer.Installer
diff --git a/worthless/__main__.py b/worthless/__main__.py
index 1426c6a..c3a60a9 100755
--- a/worthless/__main__.py
+++ b/worthless/__main__.py
@@ -1,6 +1,6 @@
 #!/usr/bin/python3
 
-import gui as gui
+from worthless import gui
 
 if __name__ == '__main__':
     gui.main()
diff --git a/worthless/classes/installer/__init__.py b/worthless/classes/installer/__init__.py
new file mode 100644
index 0000000..3055d89
--- /dev/null
+++ b/worthless/classes/installer/__init__.py
@@ -0,0 +1,6 @@
+from worthless.classes.installer import resource, game, latest, diff, voicepack
+Resource = resource.Resource
+Game = game.Game
+Latest = latest.Latest
+Diff = diff.Diff
+Voicepack = voicepack.Voicepack
diff --git a/worthless/classes/installer/diff.py b/worthless/classes/installer/diff.py
new file mode 100644
index 0000000..55b27e8
--- /dev/null
+++ b/worthless/classes/installer/diff.py
@@ -0,0 +1,21 @@
+from worthless.classes.installer.voicepack import Voicepack
+
+
+class Diff:
+    def __init__(self, name, version, path, size, md5, is_recommended_update, voice_packs, raw):
+        self.name = name
+        self.version = version
+        self.path = path
+        self.size = size
+        self.md5 = md5
+        self.is_recommended_update = is_recommended_update
+        self.voice_packs = voice_packs
+        self.raw = raw
+
+    @staticmethod
+    def from_dict(data):
+        voice_packs = []
+        for v in data['voice_packs']:
+            voice_packs.append(Voicepack.from_dict(v))
+        return Diff(data["name"], data["version"], data["path"], data["size"], data["md5"],
+                    data["is_recommended_update"], voice_packs, data)
diff --git a/worthless/classes/installer/game.py b/worthless/classes/installer/game.py
new file mode 100644
index 0000000..0c88bb3
--- /dev/null
+++ b/worthless/classes/installer/game.py
@@ -0,0 +1,16 @@
+from worthless.classes.installer.latest import Latest
+from worthless.classes.installer.diff import Diff
+
+
+class Game:
+    def __init__(self, latest, diffs, raw):
+        self.latest = latest
+        self.diffs = diffs
+        self.raw = raw
+
+    @staticmethod
+    def from_dict(data):
+        diffs = []
+        for diff in data['diffs']:
+            diffs.append(Diff.from_dict(diff))
+        return Game(Latest.from_dict(data['latest']), diffs, data)
diff --git a/worthless/classes/installer/latest.py b/worthless/classes/installer/latest.py
new file mode 100644
index 0000000..fdae997
--- /dev/null
+++ b/worthless/classes/installer/latest.py
@@ -0,0 +1,23 @@
+from worthless.classes.installer.voicepack import Voicepack
+
+
+class Latest:
+    def __init__(self, name, version, path, size, md5, entry, voice_packs, decompressed_path, segments, raw):
+        self.name = name
+        self.version = version
+        self.path = path
+        self.size = size
+        self.md5 = md5
+        self.entry = entry
+        self.voice_packs = voice_packs
+        self.decompressed_path = decompressed_path
+        self.segments = segments
+        self.raw = raw
+
+    @staticmethod
+    def from_dict(data):
+        voice_packs = []
+        for v in data['voice_packs']:
+            voice_packs.append(Voicepack.from_dict(v))
+        return Latest(data["name"], data["version"], data["path"], data["size"], data["md5"], data["entry"],
+                      voice_packs, data["decompressed_path"], data["segments"], data)
diff --git a/worthless/classes/installer/resource.py b/worthless/classes/installer/resource.py
new file mode 100644
index 0000000..4d345d8
--- /dev/null
+++ b/worthless/classes/installer/resource.py
@@ -0,0 +1,30 @@
+from worthless.classes.installer.game import Game
+
+
+class Resource:
+    """Contains the game resource information.
+
+    Everything except `game` is not wrapped yet
+
+    Attributes:
+
+    - :class:`worthless.classes.launcher.background.Background` background: The launcher background information.
+    - :class:`worthless.classes.launcher.banner.Banner` banner: The launcher banner information.
+    - :class:`worthless.classes.launcher.iconbutton.IconButton` icon: The launcher icon buttons information.
+    - :class:`worthless.classes.launcher.qq.QQ` post: The launcher QQ posts information.
+    - :class:`dict` raw: The launcher raw information.
+    """
+    def __init__(self, game, plugin, web_url, force_update, pre_download_game, deprecated_packages, sdk, raw):
+        self.game = game
+        self.plugin = plugin
+        self.web_url = web_url
+        self.force_update = force_update
+        self.pre_download_game = pre_download_game
+        self.deprecated_packages = deprecated_packages
+        self.sdk = sdk
+        self.raw = raw
+
+    @staticmethod
+    def from_dict(data):
+        return Resource(Game.from_dict(data['game']), data['plugin'], data['web_url'], data['force_update'],
+                        data['pre_download_game'], data['deprecated_packages'], data['sdk'], data)
diff --git a/worthless/classes/installer/voicepack.py b/worthless/classes/installer/voicepack.py
new file mode 100644
index 0000000..26c5383
--- /dev/null
+++ b/worthless/classes/installer/voicepack.py
@@ -0,0 +1,12 @@
+class Voicepack:
+    def __init__(self, language, name, path, size, md5, raw):
+        self.language = language
+        self.name = name
+        self.path = path
+        self.size = size
+        self.md5 = md5
+        self.raw = raw
+
+    @staticmethod
+    def from_dict(data):
+        return Voicepack(data["language"], data["name"], data["path"], data["size"], data["md5"], data)
diff --git a/worthless/classes/launcher/__init__.py b/worthless/classes/launcher/__init__.py
index 49b577a..a9c760c 100644
--- a/worthless/classes/launcher/__init__.py
+++ b/worthless/classes/launcher/__init__.py
@@ -1,7 +1,8 @@
-from worthless.classes.launcher import background, banner, iconbutton, iconotherlink, info, post
+from worthless.classes.launcher import background, banner, iconbutton, iconotherlink, info, post, qq
 Background = background.Background
 Banner = banner.Banner
 IconButton = iconbutton.IconButton
 IconOtherLink = iconotherlink.IconOtherLink
 Info = info.Info
 Post = post.Post
+QQ = qq.QQ
\ No newline at end of file
diff --git a/worthless/constants.py b/worthless/constants.py
index 4c69b64..db55dc4 100644
--- a/worthless/constants.py
+++ b/worthless/constants.py
@@ -1,6 +1,6 @@
 APP_NAME="worthless"
 APP_AUTHOR="tretrauit"
-LAUNCHER_API_URL_OS = "https://sdk-os-static.mihoyo.com/hk4e_global/mdk/launcher/api"
+LAUNCHER_API_URL_OS = "https://sdk-os-static.hoyoverse.com/hk4e_global/mdk/launcher/api"
 LAUNCHER_API_URL_CN = "https://sdk-static.mihoyo.com/hk4e_cn/mdk/launcher/api"
 PATCH_GIT_URL = "https://notabug.org/Krock/dawn"
 TELEMETRY_URL_LIST = [
diff --git a/worthless/gui.py b/worthless/gui.py
index 10a5f0c..9f9ee65 100755
--- a/worthless/gui.py
+++ b/worthless/gui.py
@@ -3,17 +3,24 @@
 import argparse
 import appdirs
 from pathlib import Path
-import constants
+from worthless.launcher import Launcher
+from worthless.installer import Installer
+import worthless.constants as constants
 
 
 class UI:
     def __init__(self, gamedir: str, noconfirm: bool) -> None:
         self._noconfirm = noconfirm
         self._gamedir = gamedir
+        self._launcher = Launcher(gamedir)
+        self._installer = Installer(gamedir)
 
     def _ask(self, title, description):
         raise NotImplementedError()
 
+    def get_game_version(self):
+        print(self._installer.get_game_version())
+
     def install_game(self):
         # TODO
         raise NotImplementedError("Install game is not implemented.")
@@ -38,7 +45,7 @@ def main():
                         help="Specify the temporary directory (default {} and {})".format(default_dirs.user_data_dir,
                                                                                       default_dirs.user_cache_dir))
     parser.add_argument("-S", "--install", action="store_true",
-                        help="Install the game (if not already installed, else do nothing)")
+                        help="Install/update the game (if not already installed, else do nothing)")
     parser.add_argument("-U", "--install-from-file", action="store_true",
                         help="Install the game from the game archive (if not already installed, \
                         else update from archive)")
@@ -46,21 +53,28 @@ def main():
                         help="Patch the game (if not already patched, else do nothing)")
     parser.add_argument("-Sy", "--update", action="store_true",
                         help="Update the game and specified voiceover pack only (or install if not found)")
+    parser.add_argument("-Sv", "--update-voiceover", action="store_true",
+                        help="Update the voiceover pack only (or install if not found)")
     parser.add_argument("-Syu", "--update-all", action="store_true",
                         help="Update the game and all installed voiceover packs (or install if not found)")
     parser.add_argument("-Rs", "--remove", action="store_true", help="Remove the game (if installed)")
     parser.add_argument("-Rp", "--remove-patch", action="store_true", help="Revert the game patch (if patched)")
     parser.add_argument("-Rv", "--remove-voiceover", action="store_true", help="Remove a Voiceover pack (if installed)")
+    parser.add_argument("--get-game-version", action="store_true", help="Get the current game version")
+    parser.add_argument("--no-overseas", action="store_true", help="Don't use overseas server")
     parser.add_argument("--noconfirm", action="store_true",
                         help="Do not ask any for confirmation. (Ignored in interactive mode)")
     args = parser.parse_args()
     interactive_mode = not args.install and not args.install_from_file and not args.patch and not args.update and not \
-        args.remove and not args.remove_patch and not args.remove_voiceover
+        args.remove and not args.remove_patch and not args.remove_voiceover and not args.get_game_version
     ui = UI(args.dir, args.noconfirm)
 
     if args.install and args.update:
         raise ValueError("Cannot specify both --install and --update arguments.")
 
+    if args.get_game_version:
+        ui.get_game_version()
+
     if args.install:
         ui.install_game()
 
diff --git a/worthless/installer.py b/worthless/installer.py
index b057860..7ad21dd 100644
--- a/worthless/installer.py
+++ b/worthless/installer.py
@@ -7,27 +7,35 @@ from worthless import constants
 from worthless.launcher import Launcher
 
 
+def _read_version_from_game_file(globalgamemanagers: Path):
+    with globalgamemanagers.open("rb") as f:
+        data = f.read().decode("ascii", errors="ignore")
+    result = re.search(r"([1-9]+\.[0-9]+\.[0-9]+)_[\d]+_[\d]+", data)
+    if not result:
+        raise ValueError("Could not find version in game file")
+    return result.group(1)
+
+
 class Installer:
     def _read_version_from_config(self):
-        if self._config_file.exists():
+        if not self._config_file.exists():
             raise FileNotFoundError(f"Config file {self._config_file} not found")
         cfg = ConfigParser()
         cfg.read(str(self._config_file))
-        return cfg.get("miHoYo", "game_version")
+        return cfg.get("General", "game_version")
 
     # https://gitlab.com/KRypt0n_/an-anime-game-launcher/-/blob/main/src/ts/Game.ts#L26
-    def _read_version_from_game_file(self):
-        if self._overseas:
-            globalgamemanagers = self._gamedir.joinpath("./GenshinImpact_Data/globalgamemanagers")
+    def get_game_version(self):
+        if self._config_file.exists():
+            return self._read_version_from_config()
         else:
-            globalgamemanagers = self._gamedir.joinpath("./YuanShen_Data/globalgamemanagers")
-        if globalgamemanagers.exists():
-            with globalgamemanagers.open("rb") as f:
-                data = f.read().decode("ascii")
-            result = re.search(r"([1-9]+\.[0-9]+\.[0-9]+)_[\d]+_[\d]+", data)
-            if not result:
-                raise ValueError("Could not find version in game file")
-            return result.group(1)
+            if self._overseas:
+                globalgamemanagers = self._gamedir.joinpath("./GenshinImpact_Data/globalgamemanagers")
+            else:
+                globalgamemanagers = self._gamedir.joinpath("./YuanShen_Data/globalgamemanagers")
+            if not globalgamemanagers.exists():
+                return
+            return _read_version_from_game_file(globalgamemanagers)
 
     def __init__(self, gamedir: str | Path = Path.cwd(), overseas: bool = True, data_dir: str | Path = None):
         if isinstance(gamedir, str):
@@ -44,9 +52,24 @@ class Installer:
         self._config_file = config_file.resolve()
         self._version = None
         self._overseas = overseas
-        self._launcher = Launcher(self._gamedir, self._overseas)
-        if config_file.exists():
-            self._version = self._read_version_from_config()
-        elif gamedir.joinpath("./GenshinImpact_Data/globalgamemanagers").exists():
-            self._version = self._read_version_from_game_file()
+        self._launcher = Launcher(self._gamedir, overseas=self._overseas)
+        self._version = self.get_game_version()
 
+    async def get_game_diff_archive(self, from_version: str = None):
+        """Gets a diff archive from `from_version` to the latest one
+
+        If from_version is not specified, it will be taken from the game version.
+        """
+        if not from_version:
+            if self._version:
+                from_version = self._version
+            else:
+                from_version = self._version = self.get_game_version()
+        if not from_version:
+            raise ValueError("No game version found")
+        game_resource = await self._launcher.get_resource_info()
+        if not game_resource:
+            raise ValueError("Could not fetch game resource")
+        for v in game_resource.game.diffs:
+            if v.version == from_version:
+                return v
diff --git a/worthless/launcher.py b/worthless/launcher.py
index 59aa2fb..a320e90 100644
--- a/worthless/launcher.py
+++ b/worthless/launcher.py
@@ -2,7 +2,36 @@ import aiohttp
 import locale
 from worthless import constants
 from pathlib import Path
-from worthless.classes import launcher
+from worthless.classes import launcher, installer
+
+
+async def _get(url, **kwargs) -> dict:
+    # Workaround because miHoYo uses retcode for their API instead of HTTP status code
+    async with aiohttp.ClientSession() as session:
+        rsp = await session.get(url, **kwargs)
+        rsp_json = await rsp.json()
+        if rsp_json["retcode"] != 0:
+            # TODO: Add more information to the error message
+            raise aiohttp.ClientResponseError(code=rsp_json["retcode"],
+                                              message=rsp_json["message"],
+                                              history=rsp.history,
+                                              request_info=rsp.request_info)
+        return rsp_json
+
+
+def _get_system_language() -> str:
+    """Gets system language compatible with server parameters.
+
+    Return:
+         System language with format xx-xx.
+    """
+
+    try:
+        lang = locale.getdefaultlocale()[0]
+        lowercase_lang = lang.lower().replace("_", "-")
+        return lowercase_lang
+    except ValueError:
+        return "en-us"  # Fallback to English if locale is not supported
 
 
 class Launcher:
@@ -10,7 +39,7 @@ class Launcher:
     Contains functions to get information from server and client like the official launcher.
     """
 
-    def __init__(self, gamedir=Path.cwd(), language=None, overseas=True):
+    def __init__(self, gamedir: str | Path = Path.cwd(), language: str = None, overseas=True):
         """Initialize the launcher API
 
         Args:
@@ -23,7 +52,7 @@ class Launcher:
                 "key": "gcStgarh",
                 "launcher_id": "10",
             }
-            self._lang = self._get_system_language() if not language else language.lower().replace("_", "-")
+            self._lang = language.lower().replace("_", "-") if language else _get_system_language()
         else:
             self._api = constants.LAUNCHER_API_URL_CN
             self._params = {
@@ -36,42 +65,13 @@ class Launcher:
             gamedir = Path(gamedir)
         self._gamedir = gamedir.resolve()
 
-    @staticmethod
-    async def _get(url, **kwargs) -> dict:
-        # Workaround because miHoYo uses retcode for their API instead of HTTP status code
-        async with aiohttp.ClientSession() as session:
-            rsp = await session.get(url, **kwargs)
-            rsp_json = await rsp.json()
-            if rsp_json["retcode"] != 0:
-                # TODO: Add more information to the error message
-                raise aiohttp.ClientResponseError(code=rsp_json["retcode"],
-                                                  message=rsp_json["message"],
-                                                  history=rsp.history,
-                                                  request_info=rsp.request_info)
-            return rsp_json
-
-    @staticmethod
-    def _get_system_language() -> str:
-        """Gets system language compatible with server parameters.
-
-        Return:
-             System language with format xx-xx.
-        """
-
-        try:
-            lang = locale.getdefaultlocale()[0]
-            lowercase_lang = lang.lower().replace("_", "-")
-            return lowercase_lang
-        except ValueError:
-            return "en-us"  # Fallback to English if locale is not supported
-
     async def _get_launcher_info(self, adv=True) -> launcher.Info:
         params = self._params | {"filter_adv": str(adv).lower(),
                                  "language": self._lang}
-        rsp = await self._get(self._api + "/content", params=params)
+        rsp = await _get(self._api + "/content", params=params)
         if rsp["data"]["adv"] is None:
             params["language"] = "en-us"
-            rsp = await self._get(self._api + "/content", params=params)
+            rsp = await _get(self._api + "/content", params=params)
         lc_info = launcher.Info.from_dict(rsp["data"])
         return lc_info
 
@@ -94,7 +94,7 @@ class Launcher:
 
         self._lang = language.lower().replace("_", "-")
 
-    async def get_version_info(self) -> dict:
+    async def get_resource_info(self) -> installer.Resource:
         """Gets version info from the server.
 
         This function gets version info including audio pack and their download url from the server.
@@ -105,8 +105,8 @@ class Launcher:
             aiohttp.ClientResponseError: An error occurred while fetching the information.
         """
 
-        rsp = await self._get(self._api + "/resource", params=self._params)
-        return rsp
+        rsp = await _get(self._api + "/resource", params=self._params)
+        return installer.Resource.from_dict(rsp["data"])
 
     async def get_launcher_info(self) -> launcher.Info:
         """Gets short launcher info from the server
@@ -143,16 +143,3 @@ class Launcher:
 
         rsp = await self.get_launcher_info()
         return rsp.background.background
-
-    async def get_system_game_info(self, table_handle, keys, require_all_keys):
-        # TODO: Implement
-        raise NotImplementedError("Not implemented yet.")
-        pass
-
-    async def get_system_game_version(self) -> str:
-        """Gets the game version from the current system.
-        :return: str: System game version.
-        """
-
-        rsp = await self.get_version_info()
-        return rsp["data"]["system"]["game_version"]