diff --git a/dworp/observer.py b/dworp/observer.py
index 75765bc..61321c7 100644
--- a/dworp/observer.py
+++ b/dworp/observer.py
@@ -53,7 +53,10 @@ class ChainedObserver(Observer):
         *observers: Variable length arguments of Observer objects
     """
     def __init__(self, *observers):
-        self.observers = observers
+        self.observers = list(observers)
+
+    def append(self, observer):
+        self.observers.append(observer)
 
     def start(self, time, agents, env):
         for observer in self.observers:
diff --git a/examples/segregation.py b/examples/segregation.py
index 49e2dcc..0555929 100644
--- a/examples/segregation.py
+++ b/examples/segregation.py
@@ -2,10 +2,13 @@
 import dworp
 import dworp.plot
 import logging
-import matplotlib.colors
-import matplotlib.pyplot as plt
 import numpy as np
-import seaborn as sns
+import sys
+try:
+    import pygame
+except ImportError:
+    # vis will be turned off
+    pass
 
 
 class Household(dworp.Agent):
@@ -112,35 +115,43 @@ def test(self, time, agents, env):
         return SegObserver.get_happiness(agents) >= 100
 
 
-class HeatmapPlotObserver(dworp.Observer):
-    """Plot the segregration grid"""
-    def __init__(self, colors):
-        self.data = None
-        self.colors = colors
-        cmap = matplotlib.colors.ListedColormap([colors[0], "white", colors[1]])
-        self.options = {
-            'cmap': cmap, 'cbar': False, 'linewidths': 0.2,
-            'xticklabels': False, 'yticklabels': False
-        }
+class PyGameRenderer(dworp.Observer):
+    def __init__(self, size, zoom, fps):
+        self.zoom = zoom
+        self.fps = fps
+        self.width = size[0]
+        self.height = size[1]
+
+        pygame.init()
+        pygame.display.set_caption("Segregation")
+        self.screen = pygame.display.set_mode((self.zoom * self.width, self.zoom * self.height))
+        self.background = pygame.Surface((self.screen.get_size()))
+        self.background = self.background.convert()
+        self.clock = pygame.time.Clock()
 
     def start(self, time, agents, env):
-        self.data = np.zeros(env.grid.data.shape)
-        plt.ion()
-        self.plot(env.grid)
+        self.draw(agents)
 
     def step(self, time, agents, env):
-        self.plot(env.grid)
+        self.draw(agents)
 
-    def plot(self, grid):
-        for x in range(self.data.shape[0]):
-            for y in range(self.data.shape[1]):
-                if grid.data[x, y] is None:
-                    self.data[x, y] = 0
-                elif grid.data[x, y].color == self.colors[0]:
-                    self.data[x, y] = -1
-                else:
-                    self.data[x, y] = 1
-        sns.heatmap(self.data, **self.options)
+    def done(self, agents, env):
+        pygame.quit()
+
+    def draw(self, agents):
+        side = self.zoom - 1
+        self.background.fill((255, 255, 255))
+        for agent in agents:
+            x = self.zoom * agent.x
+            y = self.zoom * agent.y
+            color = (255, 128, 0) if agent.color == "orange" else (0, 0, 255)
+            pygame.draw.rect(self.background, color, (x, y, side, side), 0)
+        self.screen.blit(self.background, (0, 0))
+        pygame.display.flip()
+        self.clock.tick(self.fps)
+        for event in pygame.event.get():
+            if event.type == pygame.QUIT:
+                quit()
 
 
 class SegregationParams:
@@ -186,6 +197,9 @@ def __init__(self, params, observer):
     parser.add_argument("--similar", help="desired similarity (0-100)", default=30, type=int)
     parser.add_argument("--size", help="grid size formatted as XXXxYYY", default="50x50")
     parser.add_argument("--seed", help="seed of RNG", default=42, type=int)
+    parser.add_argument("--fps", help="frames per second", default="2", type=int)
+    parser.add_argument("--no-vis", dest='vis', action='store_false')
+    parser.set_defaults(vis=True)
     args = parser.parse_args()
 
     # prepare parameters of simulation
@@ -195,14 +209,16 @@ def __init__(self, params, observer):
     similarity = args.similar / float(100)
     grid_size = [int(dim) for dim in args.size.split("x")]
     seed = args.seed
+    vis_flag = args.vis and 'pygame' in sys.modules
+    # vis does not support different colors
     colors = ["blue", "orange"]
     params = SegregationParams(density, similarity, grid_size, seed, colors)
 
     # create and run one realization of the simulation
     observer = dworp.ChainedObserver(
         SegObserver(),
-        HeatmapPlotObserver(colors),
-        dworp.plot.PlotPauseObserver(delay=1, start=True)
     )
+    if vis_flag:
+        observer.append(PyGameRenderer(grid_size, 10, args.fps))
     sim = SegregationSimulation(params, observer)
     sim.run()
diff --git a/tests/test_observer.py b/tests/test_observer.py
index 66b2831..372cc75 100644
--- a/tests/test_observer.py
+++ b/tests/test_observer.py
@@ -40,6 +40,17 @@ def test_stop_called_for_all_observers(self):
         self.assertEqual([mock.call.stop([], None)], obs1.mock_calls)
         self.assertEqual([mock.call.stop([], None)], obs2.mock_calls)
 
+    def test_append(self):
+        obs1 = mock.create_autospec(spec=Observer)
+        obs2 = mock.create_autospec(spec=Observer)
+        obs = ChainedObserver(obs1)
+        obs.append(obs2)
+
+        obs.step(1, [], None)
+
+        self.assertEqual([mock.call.step(1, [], None)], obs1.mock_calls)
+        self.assertEqual([mock.call.step(1, [], None)], obs2.mock_calls)
+
 
 class KeyPauseObserverTest(unittest.TestCase):
     def setUp(self):