diff --git a/extra/terrain/shaders/shaders.factor b/extra/terrain/shaders/shaders.factor
index c341545956..bfb46b8ba1 100644
--- a/extra/terrain/shaders/shaders.factor
+++ b/extra/terrain/shaders/shaders.factor
@@ -1,6 +1,40 @@
 USING: multiline ;
 IN: terrain.shaders
 
+STRING: sky-vertex-shader
+
+uniform float sky_theta;
+varying vec3 direction;
+
+void main()
+{
+    vec4 v = vec4(gl_Vertex.xy, -1.0, 1.0);
+    gl_Position = v;
+    float s = sin(sky_theta), c = cos(sky_theta);
+    direction = mat3(1, 0, 0,  0, c, s,  0, -s, c)
+        * (gl_ModelViewMatrixInverse * vec4(v.xyz, 0.0)).xyz;
+}
+
+;
+
+STRING: sky-pixel-shader
+
+uniform sampler2D sky;
+uniform float sky_gradient, sky_theta;
+
+const vec4 SKY_COLOR_A = vec4(0.25, 0.0, 0.5,  1.0),
+           SKY_COLOR_B = vec4(0.6,  0.5, 0.75, 1.0);
+
+varying vec3 direction;
+
+void main()
+{
+    float t = texture2D(sky, normalize(direction.xyz).xy * 0.5 + vec2(0.5)).x + sky_gradient;
+    gl_FragColor = mix(SKY_COLOR_A, SKY_COLOR_B, sin(6.28*t));
+}
+
+;
+
 STRING: terrain-vertex-shader
 
 uniform sampler2D heightmap;
diff --git a/extra/terrain/terrain.factor b/extra/terrain/terrain.factor
index 590244ca6a..411d34f44c 100644
--- a/extra/terrain/terrain.factor
+++ b/extra/terrain/terrain.factor
@@ -5,20 +5,23 @@ math.vectors opengl opengl.capabilities opengl.gl
 opengl.shaders opengl.textures opengl.textures.private
 sequences sequences.product specialized-arrays.float
 terrain.generation terrain.shaders ui ui.gadgets
-ui.gadgets.worlds ui.pixel-formats game-worlds method-chains ;
+ui.gadgets.worlds ui.pixel-formats game-worlds method-chains
+math.affine-transforms noise ;
 IN: terrain
 
 CONSTANT: FOV $[ 2.0 sqrt 1+ ]
-CONSTANT: NEAR-PLANE $[ 1.0 2048.0 / ]
-CONSTANT: FAR-PLANE 1.0
+CONSTANT: NEAR-PLANE $[ 1.0 1024.0 / ]
+CONSTANT: FAR-PLANE 2.0
 CONSTANT: PLAYER-START-LOCATION { 0.5 0.51 0.5 }
-CONSTANT: PLAYER-HEIGHT $[ 3.0 1024.0 / ]
+CONSTANT: PLAYER-HEIGHT $[ 1.0 256.0 / ]
 CONSTANT: GRAVITY $[ 1.0 4096.0 / ]
 CONSTANT: JUMP $[ 1.0 1024.0 / ]
 CONSTANT: MOUSE-SCALE $[ 1.0 10.0 / ]
 CONSTANT: MOVEMENT-SPEED $[ 1.0 16384.0 / ]
 CONSTANT: FRICTION 0.95
-CONSTANT: COMPONENT-SCALE { 0.5 0.01 0.002 0.0 }
+CONSTANT: COMPONENT-SCALE { 0.5 0.01 0.0005 0.0 }
+CONSTANT: SKY-PERIOD 1200
+CONSTANT: SKY-SPEED 0.0005
 
 CONSTANT: terrain-vertex-size { 512 512 }
 CONSTANT: terrain-vertex-distance { $[ 1.0 512.0 / ] $[ 1.0 512.0 / ] }
@@ -29,6 +32,7 @@ TUPLE: player
 
 TUPLE: terrain-world < game-world
     player
+    sky-image sky-texture sky-program
     terrain terrain-segment terrain-texture terrain-program
     terrain-vertex-buffer ;
 
@@ -41,7 +45,7 @@ M: terrain-world tick-length
     NEAR-PLANE FAR-PLANE ;
 
 : set-modelview-matrix ( gadget -- )
-    GL_COLOR_BUFFER_BIT GL_DEPTH_BUFFER_BIT bitor glClear
+    GL_DEPTH_BUFFER_BIT glClear
     GL_MODELVIEW glMatrixMode
     glLoadIdentity
     player>>
@@ -175,24 +179,33 @@ M: terrain-world tick*
     [ dup focused?>> [ handle-input ] [ drop ] if ]
     [ dup player>> tick-player ] bi ;
 
-: set-heightmap-texture-parameters ( texture -- )
+: set-texture-parameters ( texture -- )
     GL_TEXTURE_2D GL_TEXTURE0 bind-texture-unit
     GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER GL_LINEAR glTexParameteri
     GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER GL_LINEAR glTexParameteri
     GL_TEXTURE_2D GL_TEXTURE_WRAP_S GL_CLAMP_TO_EDGE glTexParameteri
     GL_TEXTURE_2D GL_TEXTURE_WRAP_T GL_CLAMP_TO_EDGE glTexParameteri ;
 
+: sky-gradient ( world -- t )
+    game-loop>> tick-number>> SKY-PERIOD mod SKY-PERIOD /f ;
+: sky-theta ( world -- theta )
+    game-loop>> tick-number>> SKY-SPEED * ;
+
 BEFORE: terrain-world begin-world
     "2.0" { "GL_ARB_vertex_buffer_object" "GL_ARB_shader_objects" }
     require-gl-version-or-extensions
     GL_DEPTH_TEST glEnable
     GL_TEXTURE_2D glEnable
     GL_VERTEX_ARRAY glEnableClientState
-    0.5 0.5 0.5 1.0 glClearColor
     PLAYER-START-LOCATION 0.0 0.0 { 0.0 0.0 0.0 } player boa >>player
+    <perlin-noise-table> 0.01 0.01 <scale> { 512 512 } perlin-noise-image
+    [ >>sky-image ] keep
+    make-texture [ set-texture-parameters ] keep >>sky-texture
     <terrain> [ >>terrain ] keep
     { 0 0 } terrain-segment [ >>terrain-segment ] keep
-    make-texture [ set-heightmap-texture-parameters ] keep >>terrain-texture
+    make-texture [ set-texture-parameters ] keep >>terrain-texture
+    sky-vertex-shader sky-pixel-shader <simple-gl-program>
+    >>sky-program
     terrain-vertex-shader terrain-pixel-shader <simple-gl-program>
     >>terrain-program
     vertex-array >vertex-buffer >>terrain-vertex-buffer
@@ -203,6 +216,8 @@ AFTER: terrain-world end-world
         [ terrain-vertex-buffer>> delete-gl-buffer ]
         [ terrain-program>> delete-gl-program ]
         [ terrain-texture>> delete-texture ]
+        [ sky-program>> delete-gl-program ]
+        [ sky-texture>> delete-texture ]
     } cleave ;
 
 M: terrain-world resize-world
@@ -212,14 +227,22 @@ M: terrain-world resize-world
     [ frustum glFrustum ] bi ;
 
 M: terrain-world draw-world*
-    [ set-modelview-matrix ]
-    [ terrain-texture>> GL_TEXTURE_2D GL_TEXTURE0 bind-texture-unit ]
-    [ dup terrain-program>> [
-        [ "heightmap" glGetUniformLocation 0 glUniform1i ]
-        [ "component_scale" glGetUniformLocation COMPONENT-SCALE first4 glUniform4f ] bi
-        terrain-vertex-buffer>> draw-vertex-buffer
-    ] with-gl-program ]
-    tri gl-error ;
+    {
+        [ set-modelview-matrix ]
+        [ terrain-texture>> GL_TEXTURE_2D GL_TEXTURE0 bind-texture-unit ]
+        [ sky-texture>> GL_TEXTURE_2D GL_TEXTURE1 bind-texture-unit ]
+        [ GL_DEPTH_TEST glDisable dup sky-program>> [
+            [ nip "sky" glGetUniformLocation 1 glUniform1i ]
+            [ "sky_gradient" glGetUniformLocation swap sky-gradient glUniform1f ]
+            [ "sky_theta" glGetUniformLocation swap sky-theta glUniform1f ] 2tri
+            { -1.0 -1.0 } { 2.0 2.0 } gl-fill-rect
+        ] with-gl-program ]
+        [ GL_DEPTH_TEST glEnable dup terrain-program>> [
+            [ "heightmap" glGetUniformLocation 0 glUniform1i ]
+            [ "component_scale" glGetUniformLocation COMPONENT-SCALE first4 glUniform4f ] bi
+            terrain-vertex-buffer>> draw-vertex-buffer
+        ] with-gl-program ]
+    } cleave gl-error ;
 
 M: terrain-world pref-dim* drop { 640 480 } ;