main.py

from kivy.config import Config

xwidth, xheight = 1024, 960
Config.set("graphics", "width", xwidth)
Config.set("graphics", "height", xheight)
Config.write()

from kivy.app import App

from kivy.core.window import Window
from kivy.uix.widget import Widget
from kivy.properties import NumericProperty, ObjectProperty
from kivy.vector import Vector
from kivy.clock import Clock

class MyKeyboardListener(Widget):
    def __init__(self, **kwargs):
        super(MyKeyboardListener, self).__init__()
        self._keyboard = Window.request_keyboard(self._keyboard_closed,"text")
        self._keyboard.bind(on_key_down=self._on_keyboard_down)
        self._keyboard.bind(on_key_up=self._on_keyboard_up)
        self.keyup = None
        self.keydown = None
    
    def _keyboard_closed(self):
        print "Keyboard Closed"
        self._keyboard.unbind(on_key_down=self._on_keyboard_down)
        self._keyboard = None
        
    def _on_keyboard_down(self, keyboard, keycode, text, modifiers):
        if keycode[1] == "escape":
            keyboard.release()
        self.keydown = text

    def _on_keyboard_up(self, keyboard, keycode):
        pass

class MyPlayer(Widget):
    pos = [450, 300]

    def move(self, key):
        if key == "w":
            self.pos[1] += 5
        print self.pos
        

class MyGame(Widget):
    player = ObjectProperty(None)
    keyboard = ObjectProperty(None)

    def __init__(self):
        super(MyGame, self).__init__()
        self.delta = 0.0
        

    def update(self, dt):
        self.player.move(self.keyboard.keydown)

class MyApp(App):
    def build(self):
        game = MyGame()
        Clock.schedule_interval(game.update, 1.0/60.0)
        return game

MyApp().run()

my.kv

#:kivy 1.7.2

<MyPlayer>
    size: 20, 20
    canvas:
        Color: 
            rgba: 1, 0, 0, 1
        Rectangle:
            pos: self.pos
            size: self.size

<MyGame>
    player: player
    keyboard: keyboard

    MyPlayer:
        id: player
    MyKeyboardListener:
        id: keyboard