checking in

I can't quite get the game to work. It keeps crashing when the
asteroid gets to the bottom.

asteroid.py

@@ -2,3 +2,22 @@
 # ------------
 # By MWC Contributors
 # This module defines an asteroid agent class.
+
+class Asteroid:
+    character = '0'
+
+    def __init__(self, position):
+        self.position = position
+
+    def play_turn(self,game):
+        if game.turn_number % 2 ==0:
+            x,y = self.position
+            if y == HEIGHT - 1: #need to rename as height
+                game.remove_agent_by_name(name.self)
+            else:
+                ship = game.get_agent_by_name('ship')
+                new_position = (x, y + 1)
+                if new_position == ship.position:
+                    game.end()
+                else:
+                    self.position = new_position

asteroid_spawner.py

@@ -2,3 +2,22 @@
 # -------------------
 # By MWC Contributors
 # This module defines an AsteroidSpawner agent class.
+
+from random import randint
+from asteroid import Asteroid
+
+class AsteroidSpawner:
+    display = False
+
+    def __init__(self, board_size):
+        width, height = board_size
+        self.board_width = width
+
+    def play_turn(self,game):
+        game.state['score'] += 1
+        if self.should_spawn_asteroid(game.turn_number):
+            asteroid = Asteroid((randint(0,self.board_width -1), 0))
+            game.add_agent(asteroid)
+    
+    def should_spawn_asteroid(self, turn_number):
+        return randint(0,1000) < turn_number

nav_game.py

@@ -2,3 +2,15 @@
 # ------------
 # By MWC Contributors
 # This class implements a simple game where a spaceship avoids asteroids.
+
+from retro.game import Game
+from spaceship import Spaceship
+from asteroid_spawner import AsteroidSpawner
+
+width = 25
+height = 25
+board_size = (width,height)
+ship = Spaceship(board_size)
+spawner = AsteroidSpawner(board_size)
+game = Game([ship, spawner], {"score": 0}, board_size = board_size)
+game.play()

new_game.py

@@ -0,0 +1,7 @@
+from retro.game import Game
+from retro.agent import ArrowKeyAgent
+
+agent = ArrowKeyAgent()
+state = {}
+game = Game([agent], state)
+game.play()

spaceship.py

@@ -2,3 +2,25 @@
 # ------------
 # By MWC Contributors
 # This module defines a spaceship agent class.
+
+class Spaceship:
+    name = "ship"
+    character = '^'
+
+    def __init__(self,board_size):
+        board_width, board_height = board_size
+        self.position = (board_width // 2, board_height -1)
+
+    def handle_keystroke(self, keystroke, game):
+        x,y = self.position
+        if keystroke.name in ("KEY_LEFT", "KEY_RIGHT"):
+            if keystroke.name == "KEY_LEFT":
+                new_position = (x-1,y)
+            else:
+                new_position = (x+1, y)
+        if game.on_board(new_position):
+            if game.is_empty(new_position):
+                self.position = new_position
+            else:
+                game.end()
+