Light Bike

It's time to build a tron-esque light bike game. If you don't know what it is, click the above link and play a few rounds.

The basic idea is that your motorcycle has a trail which never goes away... unless you crash. You can crash by either hitting the walls or any of the light trails--including your own.

Directions:

You need to create this program using classes. You may NOT use sgfx... at all. By using classes, I mean you should not have a massively complex process of if-then statements. Those webs of logic you are used to creating should be broken up into smaller digestible pieces we will use as methods in the larger class.
Your animation loop CANNOT be a naked while loop like you used in the paddle ball program "Bounce". You need to define a mainloop function and embed the while loop in this function. The game will start when you call mainloop() at the end of the program.
Your code must be commented for full credit!
Your game must be two-player.
You must have text on the screen indicating which player is which based on color.
You must have a counter on the screen which either displays the score of multiple matches or the elapsed time of a single match.

Extension:

Give the user an option to play again or quit
Give the user an option to play again or quit on the window/canvas so they don't have to go back to the interpreter.

Requirements

Think through the process with me for a moment.

Step 1: We need to leave a trail behind our bike. I can think of two options to do this.

Option 1: Move a bike around a screen and place a trail behind the bike.
Option 2: Place new bikes on the screen in the direction we want to go. I suggest going this route.

Step 2: Create a bike that leaves a trail and responds to keyboard controls for direction.

Step 3: Your bike needs to crash when it runs into walls

Step 4: Your bike needs to crash when it runs into its own trail.

Step 5: You need an opponent to play against.

Step 6: Display text on the screen showing the winner and the amount of time the game lasted and/or the score.

Extension!!

Step 7: Give the user an option to play again or quit.

Step 8: Give the player an option to play again by using your window/canvas rather than having to back to the shell.

Hint:
Here's the classes and methods I used for the program up to step 6. Once I started step 7 I created a 'game' class which allowed the program to run multiple times.

class Bike (object):
def __init__(self,color):

def turn_left(self, evt):
#changes the self.x, self.y based on keyboard event.

def turn_right(self, evt):
#changes the self.x, self.y based on keyboard event.

def turn_up(self, evt):
#changes the self.x, self.y based on keyboard event.

def turn_down(self, evt):
#changes the self.x, self.y based on keyboard event.

def MoveBike(self):
#Places the position of the self.id rectangle into the both_trails array.
   #Creates new rectangles on the screen based on the
  self.x and self.y given by the turn_left, turn_right, turn_up, turn_down methods above.

def checkhit(self):
#check to see if your position is in the both_trails array.

def new_game(self, game):
#you only need this for the extension.

---
class Bike2(Bike):
#this inherits everything from the Bike1 class, unless you decide to change it.
#because you need a second bike with different key bindings.

   def __init__(self, color):

def new_game(self, game):
#you only need this for the extensions.

---
def mainloop():
#this should contain the while loop used to animate the paddle ball game.

both_trails = []

#declare the Bike objects
Bike1 = Bike(game, 'Red')
Bike2 = Bike2(game, 'Blue')

#run the game
mainloop()