from tkinter import *
root = Tk()
root.geometry("100x100")
btn = Button(root, text = 'Играть', background="#555",    
             foreground="#ccc",     
             padx="10",            
             pady="5",              
             font="16",
             
             )
btn.pack()

 def exitting():
    global root
    root.destroy()
    exit()
btn = Button(root, text = 'Играть', command=exitting, background="#555",    
             foreground="#ccc",     
             padx="10",            
             pady="5",              
             font="16",
             
             )