add restart button to game over screen

src/ui/GameWorldView.cpp

@@ -1121,3 +1121,24 @@ void GameWorldView::setGameSpeed(double multiplier)
                       m_sim->buildingBlocksStock(),
                       m_gameSpeedMultiplier);
 }
+
+void GameWorldView::resetForNewGame()
+{
+    exitBuilderMode();
+    m_activeBeams.clear();
+    m_toasts.clear();
+    m_ghostRotation    = Rotation::East;
+    m_ghostValid       = false;
+    m_demolishMode     = false;
+    m_demolishHoverId  = kInvalidEntityId;
+    m_selectedIds.clear();
+    m_boxSelecting     = false;
+    m_scrollXTiles     = 0.0f;
+    m_scrollLeft       = false;
+    m_scrollRight      = false;
+    m_gameOverShown    = false;
+    m_gameSpeedMultiplier  = 1.0;
+    m_prevNonZeroSpeed     = 1.0;
+    emit selectionChanged({});
+    update();
+}

src/ui/GameWorldView.h

@@ -51,6 +51,7 @@ public slots:
     void enterBuilderMode(BuildingType type);
     void exitBuilderMode();
     void setGameSpeed(double multiplier);
+    void resetForNewGame();
 
 protected:
     void initializeGL() override;

src/ui/MainWindow.cpp

@@ -2,6 +2,7 @@
 
 #include <QHBoxLayout>
 #include <QMessageBox>
+#include <QPushButton>
 #include <QResizeEvent>
 #include <QVBoxLayout>
 
@@ -106,7 +107,17 @@ void MainWindow::onGameOver()
     box.setText(QString("HQ destroyed!\nSurvival time: %1:%2")
         .arg(minutes, 2, 10, QChar('0'))
         .arg(seconds, 2, 10, QChar('0')));
+    QPushButton* restartBtn = box.addButton("Restart", QMessageBox::AcceptRole);
     box.addButton("Quit", QMessageBox::RejectRole);
     box.exec();
-    close();
+
+    if (box.clickedButton() == restartBtn)
+    {
+        m_sim->reset();
+        m_gameWorldView->resetForNewGame();
+    }
+    else
+    {
+        close();
+    }
 }