auto fullscreen option

source/funkin/Preferences.hx

@@ -330,6 +330,27 @@ class Preferences
     return value;
   }
 
+  /**
+   * If enabled, the game will automatically launch in fullscreen on startup.
+   *
+   * This does not apply on mobile devices.
+   * @default `false`
+   */
+  public static var autoFullscreen(get, set):Bool;
+
+  static function get_autoFullscreen():Bool
+  {
+    return Save?.instance?.options?.autoFullscreen ?? false;
+  }
+
+  static function set_autoFullscreen(value:Bool):Bool
+  {
+    var save:Save = Save.instance;
+    save.options.autoFullscreen = value;
+    save.flush();
+    return value;
+  }
+
   public static var unlockedFramerate(get, set):Bool;
 
   static function get_unlockedFramerate():Bool
@@ -458,14 +479,16 @@ class Preferences
    */
   public static function init():Void
   {
-    // Apply the autoPause setting (enables automatic pausing on focus lost).
+    // Apply the autoPause setting (enables automatic pausing when losing focus).
     FlxG.autoPause = Preferences.autoPause;
     flixel.FlxSprite.defaultAntialiasing = Preferences.antialiasing;
     // Apply the debugDisplay setting (enables the FPS and RAM display).
     toggleDebugDisplay(Preferences.debugDisplay);
     #if web
     toggleFramerateCap(Preferences.unlockedFramerate);
     #end
+    // Apply the autoFullscreen setting (launches the game in fullscreen automatically)
+    FlxG.fullscreen = Preferences.autoFullscreen;
     #if mobile
     // Apply the allowScreenTimeout setting (enables screen timeout).
     lime.system.System.allowScreenTimeout = Preferences.screenTimeout;

source/funkin/save/Save.hx

@@ -111,6 +111,7 @@ class Save
           showTimings: true,
           debugDisplay: true,
           autoPause: true,
+          autoFullscreen: false,
           laneAlpha: 0,
           strumAlpha: 100,
           badsShitsCauseMiss: false,
@@ -1396,6 +1397,14 @@ typedef SaveDataOptions =
    */
   var autoPause:Bool;
 
+  /**
+   * If enabled, the game will automatically launch in fullscreen on startup.
+   *
+   * This does not apply to mobile devices, obviously, hence why it only shows up on `desktop` and `web` platforms.
+   * @default `false`
+   */
+  var autoFullscreen:Bool;
+
   /**
    * How transparent should the black underlay be under the lanes?
    *

source/funkin/ui/options/PreferencesMenu.hx

@@ -241,6 +241,11 @@ class PreferencesMenu extends Page
       Preferences.judgeCounter = value;
       yeahBf(value);
     }, Preferences.judgeCounter);
+    #if (desktop || web)
+    createPrefItemCheckbox('Launch in Fullscreen', 'Enable to automatically launch the game in fullscreen on startup', function(value:Bool):Void {
+      Preferences.autoFullscreen = value;
+    }, Preferences.autoFullscreen);
+    #end
     #if web
     createPrefItemCheckbox('Unlocked Framerate', 'Enable to unlock the framerate', function(value:Bool):Void {
       Preferences.unlockedFramerate = value;
@@ -253,7 +258,7 @@ class PreferencesMenu extends Page
       else
         FlxG.game.focusLostFramerate = Preferences.framerate;
       yeahBf(false);
-    }, null, Preferences.framerate, #if mobile 60 #else 24 #end, 960, 1, 0);
+    }, null, Preferences.framerate, #if mobile 60 #else 24 #end, 360, 1, 0);
     #end
     createPrefHeader('Miscellaneous');
     createPrefItemCheckbox('Naughtiness', 'Enable so your mom won\'t scream at ya, right now it doesn\'t do much', function(value:Bool):Void {