#Turtle Graphics Game
import turtle

#Set up screen
wn = turtle.Screen()
wn.bgcolor("lightgreen")

#Draw border
mypen = turtle.Turtle()
mypen.penup()
mypen.setposition(-300, -300)
mypen.pendown()
mypen.pensize(3)
for side in range(4):
    mypen.forward(600)
    mypen.left(90)
mypen.hideturtle()

#Create player turtle
player = turtle.Turtle()
player.color("blue")
player.shape("triangle")
player.penup()

#Set speed variable
speed = 1

#Define functions

def turnleft():
    player.left(30)

def turnright():
    player.right(30)

def increasespeed():
    global speed
    speed += 1

def decreasespeed():
    global speed
    speed -= 1
    if speed < 0:
        speed = 0

#Set keyboard bindings
turtle.listen()
turtle.onkey(turnleft, "Left")
turtle.onkey(turnright, "Right")
turtle.onkey(increasespeed, "Up")
turtle.onkey(decreasespeed, "Down")

while True:
    player.forward(speed)

    #Boundary Checking
    if player.xcor() > 300 or player.xcor() < -300:
        player.right(180)

    #Boundary Checking
    if player.ycor() > 300 or player.ycor() < -300:
        player.right(180)