diff --git a/lua/client/client.lua b/lua/client/client.lua
index 0ed8b6f8..5fb8f608 100644
--- a/lua/client/client.lua
+++ b/lua/client/client.lua
@@ -21,5 +21,9 @@ freekill.client_callback["enter_lobby"] = function(json_data)
     ClientInstance:notifyUI("enter_lobby", json_data)
 end
 
+freekill.client_callback["enter_room"] = function(json_data)
+    ClientInstance:notifyUI("enter_room", json_data)
+end
+
 -- Create ClientInstance (used by Lua)
 ClientInstance = Client:new()
diff --git a/lua/server/server.lua b/lua/server/server.lua
index 67b33266..5ea55f11 100644
--- a/lua/server/server.lua
+++ b/lua/server/server.lua
@@ -15,12 +15,30 @@ function Server:initialize()
 end
 
 freekill.server_callback["create_room"] = function(json_data)
-    -- json_data: [ int id, string name, int capacity ]
+    -- json_data: [ int uid, string name, int capacity ]
     local data = json.decode(json_data)
-    local owner = freekill.ServerInstance:findPlayer(data[1])
+    local owner = freekill.ServerInstance:findPlayer(tonumber(data[1]))
     local roomName = data[2]
     local capacity = data[3]
     freekill.ServerInstance:createRoom(owner, roomName, capacity)
 end
 
+freekill.server_callback["enter_room"] = function(json_data)
+    -- json_data: [ int uid, int roomId ]
+    local data = json.decode(json_data)
+    local player = freekill.ServerInstance:findPlayer(tonumber(data[1]))
+    local room = freekill.ServerInstance:findRoom(tonumber(data[2]))
+    room:addPlayer(player)
+end
+
+freekill.server_callback["quit_room"] = function(json_data)
+    -- json_data: [ int uid ]
+    local data = json.decode(json_data)
+    local player = freekill.ServerInstance:findPlayer(tonumber(data[1]))
+    local room = player:getRoom()
+    if not room:isLobby() then
+        room:removePlayer(player)
+    end
+end
+
 ServerInstance = Server:new()
diff --git a/qml/Page/Room.qml b/qml/Page/Room.qml
deleted file mode 100644
index 22c5da15..00000000
--- a/qml/Page/Room.qml
+++ /dev/null
@@ -1,8 +0,0 @@
-import QtQuick 2.15
-import QtQuick.Controls 2.0
-import QtQuick.Window 2.0
-
-Item {
-    id: root
-}
-
diff --git a/qml/Pages/CreateRoom.qml b/qml/Pages/CreateRoom.qml
new file mode 100644
index 00000000..fe7b0397
--- /dev/null
+++ b/qml/Pages/CreateRoom.qml
@@ -0,0 +1,63 @@
+import QtQuick 2.15
+import QtQuick.Controls 2.0
+import QtQuick.Layouts 1.15
+
+Item {
+    id: root
+    Frame {
+        anchors.centerIn: parent
+        Column {
+            x: 32
+            y: 20
+            spacing: 20
+
+            RowLayout {
+                anchors.rightMargin: 8
+                spacing: 16
+                Text {
+                    text: "Room Name"
+                }
+                TextField {
+                    id: roomName
+                    font.pixelSize: 18
+                    text: "tmp's Room"
+                }
+            }
+
+            RowLayout {
+                anchors.rightMargin: 8
+                spacing: 16
+                Text {
+                    text: "Player num"
+                }
+                SpinBox {
+                    id: playerNum
+                    from: 2
+                    to: 8
+                }
+            }
+
+            RowLayout {
+                anchors.rightMargin: 8
+                spacing: 16
+                Button {
+                    text: "OK"
+                    onClicked: {
+                        mainWindow.busy = true;
+                        mainStack.pop();
+                        Backend.notifyServer(
+                            "create_room",
+                            JSON.stringify([roomName.text, playerNum.value])
+                        );
+                    }
+                }
+                Button {
+                    text: "Cancel"
+                    onClicked: {
+                        mainStack.pop();
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/qml/Page/Init.qml b/qml/Pages/Init.qml
similarity index 74%
rename from qml/Page/Init.qml
rename to qml/Pages/Init.qml
index c49f6525..35c8ce58 100644
--- a/qml/Page/Init.qml
+++ b/qml/Pages/Init.qml
@@ -1,6 +1,5 @@
 import QtQuick 2.15
 import QtQuick.Controls 2.0
-import QtQuick.Window 2.0
 
 Item {
     id: root
@@ -20,16 +19,16 @@ Item {
             Button {
                 text: "Join Server"
                 onClicked: {
-                    mainWindow.state = "busy";
-                    mainWindow.busyString = "Connecting to host...";
+                    mainWindow.busy = true;
+                    toast.show("Connecting to host...");
                     Backend.joinServer(server_addr.text);
                 }
             }
             Button {
                 text: "Console start"
                 onClicked: {
-                    mainWindow.state = "busy";
-                    mainWindow.busyString = "Connecting to host...";
+                    mainWindow.busy = true;
+                    toast.show("Connecting to host...");
                     Backend.startServer(9527);
                     Backend.joinServer("127.0.0.1");
                 }
diff --git a/qml/Page/Lobby.qml b/qml/Pages/Lobby.qml
similarity index 66%
rename from qml/Page/Lobby.qml
rename to qml/Pages/Lobby.qml
index 885b7e90..b548bc4a 100644
--- a/qml/Page/Lobby.qml
+++ b/qml/Pages/Lobby.qml
@@ -40,7 +40,13 @@ Item {
                     hoverEnabled: true
                     onEntered: {    parent.color = "blue"   }
                     onExited: { parent.color = "black"  }
-                    onClicked: {}
+                    onClicked: {
+                        mainWindow.busy = true;
+                        Backend.notifyServer(
+                            "enter_room",
+                            JSON.stringify([roomId])
+                        );
+                    }
                 }
             }
         }
@@ -85,7 +91,9 @@ Item {
             }
             Button {
                 text: "Create Room"
-                onClicked: {}
+                onClicked: {
+                    mainStack.push(createRoom);
+                }
             }
             Button {
                 text: "Generals Overview"
@@ -101,12 +109,42 @@ Item {
             }
             Button {
                 text: "Exit Lobby"
+                onClicked: {
+                    toast.show("Goodbye.");
+                    Backend.quitLobby();
+                    mainStack.pop();
+                }
             }
         }
     }
 
+    Loader {
+        id: lobby_dialog
+        z: 1000
+        onSourceChanged: {
+            if (item === null)
+                return;
+            item.finished.connect(function(){
+                source = "";
+            });
+            item.widthChanged.connect(function(){
+                lobby_dialog.moveToCenter();
+            });
+            item.heightChanged.connect(function(){
+                lobby_dialog.moveToCenter();
+            });
+            moveToCenter();
+        }
+
+        function moveToCenter()
+        {
+            item.x = Math.round((root.width - item.width) / 2);
+            item.y = Math.round(root.height * 0.67 - item.height / 2);
+        }
+    }
+
     Component.onCompleted: {
-        // toast.show("Welcome to FreeKill lobby!")
+        toast.show("Welcome to FreeKill lobby!");
     }
 }
 
diff --git a/qml/Pages/Room.qml b/qml/Pages/Room.qml
new file mode 100644
index 00000000..0c969600
--- /dev/null
+++ b/qml/Pages/Room.qml
@@ -0,0 +1,18 @@
+import QtQuick 2.15
+import QtQuick.Controls 2.0
+
+Item {
+    id: root
+    Text {
+        anchors.centerIn: parent
+        text: "You are in room."
+    }
+    Button {
+        text: "quit"
+        onClicked: {
+            mainStack.pop();
+            Backend.notifyServer("quit_room", "[]");
+        }
+    }
+}
+
diff --git a/qml/main.qml b/qml/main.qml
index 76ed0efa..e387798e 100644
--- a/qml/main.qml
+++ b/qml/main.qml
@@ -1,6 +1,7 @@
 import QtQuick 2.15
 import QtQuick.Controls 2.0
 import QtQuick.Window 2.0
+import "Pages"
 
 Window {
     id: mainWindow
@@ -10,46 +11,52 @@ Window {
     property var callbacks: ({
         "error_msg": function(json_data) {
             toast.show(json_data);
-            if (mainWindow.state === "busy")
-                mainWindow.state = "init";
+            mainWindow.busy = false;
         },
         "enter_lobby": function(json_data) {
-            mainWindow.state = "lobby";
+            if (mainStack.depth === 1) {
+                mainStack.push(lobby);
+            }
+            mainWindow.busy = false;
+        },
+        "enter_room": function(json_data) {
+            mainStack.push(room);
+            mainWindow.busy = false;
         }
     })
 
-    Loader {
-        id: mainLoader
-        source: "Page/Init.qml"
+    StackView {
+        id: mainStack
+        visible: !mainWindow.busy
+        initialItem: init
         anchors.fill: parent
     }
 
-    property string state: "init"
-
-    onStateChanged: {
-        switch (state) {
-            case "init":
-                mainLoader.source = "Page/Init.qml";
-                break;
-            case "lobby":
-                mainLoader.source = "Page/Lobby.qml";
-                break;
-            case "room":
-                mainLoader.source = "Page/Room.qml";
-                break;
-            case "busy":
-                mainLoader.source = "";
-                break;
-            default: break;
-        }
+    Component {
+        id: init
+        Init {}
     }
 
-    property string busyString: "Busy"
+    Component {
+        id: lobby
+        Lobby {}
+    }
 
+    Component {
+        id: room
+        Room {}
+    }
+
+    Component {
+        id: createRoom
+        CreateRoom {}
+    }
+
+    property bool busy: false
     BusyIndicator {
         running: true
         anchors.centerIn: parent
-        visible: mainWindow.state === "busy"
+        visible: mainWindow.busy === true
     }
 
     Rectangle {
@@ -83,14 +90,14 @@ Window {
 
             ScriptAction {
                 script: {
-                    toast.opacity = 0
+                    toast.opacity = 0;
                 }
             }
         }
 
         function show(text) {
-            opacity = 1
-            toast_text.text = text
+            opacity = 1;
+            toast_text.text = text;
         }
     }
 
diff --git a/src/client/client.cpp b/src/client/client.cpp
index 5d16316e..dd27cf68 100644
--- a/src/client/client.cpp
+++ b/src/client/client.cpp
@@ -23,6 +23,7 @@ Client::Client(QObject* parent)
 Client::~Client()
 {
     ClientInstance = nullptr;
+    router->getSocket()->disconnectFromHost();
     router->getSocket()->deleteLater();
 }
 
@@ -39,12 +40,12 @@ void Client::requestServer(const QString& command, const QString& json_data, int
 
 void Client::replyToServer(const QString& command, const QString& json_data)
 {
-    int type = Router::TYPE_REQUEST | Router::SRC_CLIENT | Router::DEST_SERVER;
+    int type = Router::TYPE_REPLY | Router::SRC_CLIENT | Router::DEST_SERVER;
     router->reply(type, command, json_data);
 }
 
 void Client::notifyServer(const QString& command, const QString& json_data)
 {
-    int type = Router::TYPE_REQUEST | Router::SRC_CLIENT | Router::DEST_SERVER;
+    int type = Router::TYPE_NOTIFICATION | Router::SRC_CLIENT | Router::DEST_SERVER;
     router->notify(type, command, json_data);
 }
diff --git a/src/network/router.cpp b/src/network/router.cpp
index 51a597bc..bd446c95 100644
--- a/src/network/router.cpp
+++ b/src/network/router.cpp
@@ -3,6 +3,7 @@
 #include "router.h"
 #include "client.h"
 #include "server.h"
+#include "serverplayer.h"
 
 Router::Router(QObject *parent, ClientSocket *socket, RouterType type)
     : QObject(parent)
@@ -153,9 +154,14 @@ void Router::handlePacket(const QByteArray& rawPacket)
 
     if (type & TYPE_NOTIFICATION) {
         if (type & DEST_CLIENT) {
-            qobject_cast<Client *>(parent())->callLua(command, json_data);
+            ClientInstance->callLua(command, json_data);
         } else {
-            qDebug() << rawPacket << Qt::endl;
+            // Add the uid of sender to json_data
+            QJsonArray arr = QJsonDocument::fromJson(json_data.toUtf8()).array();
+            arr.prepend(
+                (int)qobject_cast<ServerPlayer *>(parent())->getUid()
+            );
+            ServerInstance->callLua(command, QJsonDocument(arr).toJson());
         }
     }
     else if (type & TYPE_REQUEST) {
@@ -165,7 +171,8 @@ void Router::handlePacket(const QByteArray& rawPacket)
         if (type & DEST_CLIENT) {
             qobject_cast<Client *>(parent())->callLua(command, json_data);
         } else {
-            qDebug() << rawPacket << Qt::endl;
+            // requesting server is not allowed
+            Q_ASSERT(false);
         }
     }
     else if (type & TYPE_REPLY) {
diff --git a/src/server/room.cpp b/src/server/room.cpp
index 18189d5e..1137684b 100644
--- a/src/server/room.cpp
+++ b/src/server/room.cpp
@@ -8,6 +8,10 @@ Room::Room(Server* server)
     id = roomId;
     roomId++;
     this->server = server;
+    if (!isLobby()) {
+        connect(this, &Room::playerAdded, server->lobby(), &Room::removePlayer);
+        connect(this, &Room::playerRemoved, server->lobby(), &Room::addPlayer);
+    }
 }
 
 Room::~Room()
@@ -72,7 +76,15 @@ void Room::setOwner(ServerPlayer *owner)
 
 void Room::addPlayer(ServerPlayer *player)
 {
-    players.insert(player->getId(), player);
+    if (!player) return;
+    players.insert(player->getUid(), player);
+    player->setRoom(this);
+    if (isLobby()) {
+        player->doNotify("enter_lobby", "{}");
+    } else {
+        player->doNotify("enter_room", "{}");
+    }
+    qDebug() << "Player #" << player->getUid() << " entered room";
     emit playerAdded(player);
 }
 
diff --git a/src/server/server.cpp b/src/server/server.cpp
index c08906fb..5ea9f5ac 100644
--- a/src/server/server.cpp
+++ b/src/server/server.cpp
@@ -22,6 +22,7 @@ Server::Server(QObject* parent)
 
     L = CreateLuaState();
     DoLuaScript(L, "lua/freekill.lua");
+    DoLuaScript(L, "lua/server/server.lua");
 }
 
 Server::~Server()
@@ -41,13 +42,11 @@ void Server::createRoom(ServerPlayer* owner, const QString &name, uint capacity)
     room->setName(name);
     room->setCapacity(capacity);
     room->setOwner(owner);
-    // TODO
-    // room->addPlayer(owner);
+    room->addPlayer(owner);
     rooms.insert(room->getId(), room);
 #ifdef QT_DEBUG
     qDebug() << "Room #" << room->getId() << " created.";
 #endif
-    emit roomCreated(room);
 }
 
 Room *Server::findRoom(uint id) const
@@ -75,13 +74,14 @@ void Server::processNewConnection(ClientSocket* client)
     // version check, file check, ban IP, reconnect, etc
     ServerPlayer *player = new ServerPlayer(lobby());
     player->setSocket(client);
+    players.insert(player->getUid(), player);
 #ifdef QT_DEBUG
     qDebug() << "ServerPlayer #" << player->getUid() << "connected.";
     qDebug() << "His address is " << client->peerAddress();
 #endif
 
-    player->doNotify("enter_lobby", "{}");
-
+    //player->doNotify("enter_lobby", "{}");
+    lobby()->addPlayer(player);
 }
 
 void Server::onRoomAbandoned()
diff --git a/src/ui/qmlbackend.cpp b/src/ui/qmlbackend.cpp
index b95ebb6c..f9a294be 100644
--- a/src/ui/qmlbackend.cpp
+++ b/src/ui/qmlbackend.cpp
@@ -13,10 +13,13 @@ QmlBackend::QmlBackend(QObject* parent)
 
 void QmlBackend::startServer(ushort port)
 {
-    class Server *server = new class Server(this);
-    if (!server->listen(QHostAddress::Any, port)) {
-        server->deleteLater();
-        emit notifyUI("error_msg", tr("Cannot start server!"));
+    if (!ServerInstance) {
+        class Server *server = new class Server(this);
+
+        if (!server->listen(QHostAddress::Any, port)) {
+            server->deleteLater();
+            emit notifyUI("error_msg", tr("Cannot start server!"));
+        }
     }
 }
 
@@ -50,3 +53,8 @@ void QmlBackend::notifyServer(const QString& command, const QString& json_data)
 {
     ClientInstance->notifyServer(command, json_data);
 }
+
+void QmlBackend::quitLobby()
+{
+    delete ClientInstance;
+}
diff --git a/src/ui/qmlbackend.h b/src/ui/qmlbackend.h
index 7eae0774..0e7f5373 100644
--- a/src/ui/qmlbackend.h
+++ b/src/ui/qmlbackend.h
@@ -31,6 +31,9 @@ public slots:
     void replyToServer(const QString &command, const QString &json_data);
     void notifyServer(const QString &command, const QString &json_data);
 
+    // Lobby
+    void quitLobby();
+
 private:
     WindowType type;
 };