diff --git a/basis/circular/circular-docs.factor b/basis/circular/circular-docs.factor
index c7af57c1fe..235d5db2c7 100644
--- a/basis/circular/circular-docs.factor
+++ b/basis/circular/circular-docs.factor
@@ -43,6 +43,11 @@ HELP: push-growing-circular
      { "elt" object } { "circular" circular } }
 { $description "Pushes an element onto a " { $link growing-circular } " object." } ;
 
+HELP: rotate-circular
+{ $values
+    { "circular" circular } }
+{ $description "Advances the start index of a circular object by one." } ;
+
 ARTICLE: "circular" "Circular sequences"
 "The " { $vocab-link "circular" } " vocabulary implements the " { $link "sequence-protocol" } " to allow an arbitrary start index and wrap-around indexing." $nl
 "Creating a new circular object:"
@@ -51,6 +56,7 @@ ARTICLE: "circular" "Circular sequences"
 { $subsection <growing-circular> }
 "Changing the start index:"
 { $subsection change-circular-start }
+{ $subsection rotate-circular }
 "Pushing new elements:"
 { $subsection push-circular }
 { $subsection push-growing-circular } ;
diff --git a/basis/circular/circular-tests.factor b/basis/circular/circular-tests.factor
index 105e3790aa..3a94e14640 100644
--- a/basis/circular/circular-tests.factor
+++ b/basis/circular/circular-tests.factor
@@ -12,6 +12,7 @@ circular strings ;
 [ CHAR: e ] [ "test" <circular> 5 swap nth-unsafe ] unit-test
  
 [ [ 1 2 3 ] ] [ { 1 2 3 } <circular> [ ] like ] unit-test
+[ [ 2 3 1 ] ] [ { 1 2 3 } <circular> [ rotate-circular ] keep [ ] like ] unit-test
 [ [ 2 3 1 ] ] [ { 1 2 3 } <circular> 1 over change-circular-start [ ] like ] unit-test
 [ [ 3 1 2 ] ] [ { 1 2 3 } <circular> 1 over change-circular-start 1 over change-circular-start [ ] like ] unit-test
 [ [ 3 1 2 ] ] [ { 1 2 3 } <circular> -100 over change-circular-start [ ] like ] unit-test
diff --git a/basis/circular/circular.factor b/basis/circular/circular.factor
index 9f3a71f2a8..909b2ed713 100644
--- a/basis/circular/circular.factor
+++ b/basis/circular/circular.factor
@@ -27,6 +27,9 @@ M: circular virtual-seq seq>> ;
     #! change start to (start + n) mod length
     circular-wrap (>>start) ;
 
+: rotate-circular ( circular -- )
+    [ start>> 1 + ] keep circular-wrap (>>start) ;
+
 : push-circular ( elt circular -- )
     [ set-first ] [ 1 swap change-circular-start ] bi ;
 
diff --git a/extra/game-worlds/game-worlds.factor b/extra/game-worlds/game-worlds.factor
index c9ea03e333..2fb115b5d0 100644
--- a/extra/game-worlds/game-worlds.factor
+++ b/extra/game-worlds/game-worlds.factor
@@ -12,12 +12,12 @@ M: game-world draw*
     swap >>tick-slice draw-world ;
 
 M: game-world begin-world
+    open-game-input 
     dup [ tick-length ] [ ] bi <game-loop> [ >>game-loop ] keep start-loop
-    drop
-    open-game-input ;
-
-M: game-world end-world
-    close-game-input
-    [ [ stop-loop ] when* f ] change-game-loop
+    drop ;
+
+M: game-world end-world
+    [ [ stop-loop ] when* f ] change-game-loop
+    close-game-input
     drop ;
 
diff --git a/extra/terrain/shaders/shaders.factor b/extra/terrain/shaders/shaders.factor
index e5b517ad59..108856e1dd 100644
--- a/extra/terrain/shaders/shaders.factor
+++ b/extra/terrain/shaders/shaders.factor
@@ -8,10 +8,10 @@ varying vec3 direction;
 
 void main()
 {
-    vec4 v = vec4(gl_Vertex.xy, 1.0, 1.0);
+    vec4 v = vec4(gl_Vertex.xy, -1.0, 1.0);
     gl_Position = v;
 
-    vec4 p = (gl_ProjectionMatrixInverse * v) * vec4(1,1,-1,1);
+    vec4 p = gl_ProjectionMatrixInverse * v;
     
     float s = sin(sky_theta), c = cos(sky_theta);
     direction = mat3(1, 0, 0,  0, c, s,  0, -s, c)