import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk


class MainWindow(Gtk.Window):

    def __init__(self):
        Gtk.Window.__init__(self, title="")


win = MainWindow()
win.connect("delete-event", Gtk.main_quit)
win.show_all()
Gtk.main()

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk


class MainWindow(Gtk.Window):

    def __init__(self):
        Gtk.Window.__init__(self, title="Text Playing Game")
        self.set_border_width(10)
        self.set_size_request(500, 400)


win = MainWindow()
win.connect("delete-event", Gtk.main_quit)
win.show_all()
Gtk.main()

Set GUI title and size
Set GUI title
and size
