diff --git a/doomsday/client/include/render/skydrawable.h b/doomsday/client/include/render/skydrawable.h
index 7b163fb88a..2a30685f85 100644
--- a/doomsday/client/include/render/skydrawable.h
+++ b/doomsday/client/include/render/skydrawable.h
@@ -43,13 +43,10 @@ class Sky;
 class SkyDrawable
 {
 public:
-    /// No animator is presently configured. @ingroup errors
-    DENG2_ERROR(MissingAnimatorError);
-
     /// Required model is missing. @ingroup errors
     DENG2_ERROR(MissingModelError);
 
-    struct ModelInfo
+    struct ModelData
     {
         de::Record const *def; // Sky model def
         ModelDef *model;
@@ -88,10 +85,6 @@ class SkyDrawable
 public:
     SkyDrawable();
 
-    bool hasAnimator() const;
-    void setAnimator(Animator *newAnimator);
-    Animator &animator();
-
     /**
      * Models are set up according to the given @a skyDef.
      */
@@ -100,12 +93,12 @@ class SkyDrawable
     /**
      * Cache all assets needed for visualizing the sky.
      */
-    void cacheDrawableAssets();
+    void cacheDrawableAssets(Sky const *sky = 0);
 
     /**
      * Render the sky.
      */
-    void draw();
+    void draw(Sky const *sky = 0) const;
 
     /**
      * Determines whether the specified sky model @a index is valid.
@@ -119,21 +112,17 @@ class SkyDrawable
      *
      * @see hasModel()
      */
-    ModelInfo &model(int index);
+    ModelData &model(int index);
 
     /// @copydoc model()
-    ModelInfo const &model(int index) const;
+    ModelData const &model(int index) const;
 
     /**
      * Returns a pointer to the referenced sky model; otherwise @c 0.
      *
      * @see hasModel(), model()
      */
-    inline ModelInfo *modelPtr(int index) { return hasModel(index)? &model(index) : 0; }
-
-    /// @todo RenderSystem should own a sky-masked-material => SkyDrawable map.
-    void setSky(Sky *sky);
-    Sky &sky();
+    inline ModelData *modelPtr(int index) { return hasModel(index)? &model(index) : 0; }
 
 public:
     static de::MaterialVariantSpec const &layerMaterialSpec(bool masked);
diff --git a/doomsday/client/include/world/p_ticker.h b/doomsday/client/include/world/p_ticker.h
index 323c299ccf..3f6cf29145 100644
--- a/doomsday/client/include/world/p_ticker.h
+++ b/doomsday/client/include/world/p_ticker.h
@@ -20,6 +20,10 @@
 #ifndef DENG_WORLD_P_TICKER_H
 #define DENG_WORLD_P_TICKER_H
 
+#include "world/thinkers.h"
+
+int P_MobjTicker(thinker_t *th, void *context);
+
 /**
  * Doomsday's own play-ticker.
  */
diff --git a/doomsday/client/include/world/worldsystem.h b/doomsday/client/include/world/worldsystem.h
index 0c7d532a5c..cc10a2d290 100644
--- a/doomsday/client/include/world/worldsystem.h
+++ b/doomsday/client/include/world/worldsystem.h
@@ -74,10 +74,6 @@ class WorldSystem : public de::System
     // System.
     void timeChanged(de::Clock const &);
 
-    /**
-     * To be called to register the commands and variables of this module.
-     */
-    static void consoleRegister();
 
     /**
      * To be called to reset the world back to the initial state. Any currently
@@ -131,6 +127,8 @@ class WorldSystem : public de::System
      */
     timespan_t time() const;
 
+    void tick(timespan_t elapsed);
+
 #ifdef __CLIENT__
     /**
      * To be called at the beginning of a render frame, so that we can prepare for
@@ -164,6 +162,12 @@ class WorldSystem : public de::System
 
 #endif // __CLIENT__
 
+public:
+    /**
+     * To be called to register the commands and variables of this module.
+     */
+    static void consoleRegister();
+
 private:
     DENG2_PRIVATE(d)
 };
diff --git a/doomsday/client/src/render/rend_main.cpp b/doomsday/client/src/render/rend_main.cpp
index 3848a1d244..952eea217f 100644
--- a/doomsday/client/src/render/rend_main.cpp
+++ b/doomsday/client/src/render/rend_main.cpp
@@ -3465,7 +3465,7 @@ static void drawLists(DrawLists::FoundLists const &lists, DrawMode mode)
     popGLStateForPass(mode);
 }
 
-static void drawSky()
+static void drawSky(Sky const &sky)
 {
     DrawLists::FoundLists lists;
     ClientApp::renderSystem().drawLists().findAll(SkyMaskGeom, lists);
@@ -3503,7 +3503,7 @@ static void drawSky()
     glStencilFunc(GL_EQUAL, 1, 0xffffffff);
     glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 
-    ClientApp::renderSystem().sky().draw();
+    ClientApp::renderSystem().sky().draw(&sky);
 
     if(!devRendSkyAlways)
     {
@@ -3634,7 +3634,7 @@ static void drawAllLists(Map &map)
     DENG_ASSERT_IN_MAIN_THREAD();
     DENG_ASSERT_GL_CONTEXT_ACTIVE();
 
-    drawSky();
+    drawSky(map.sky());
 
     // Render the real surfaces of the visible world.
 
diff --git a/doomsday/client/src/render/rendersystem.cpp b/doomsday/client/src/render/rendersystem.cpp
index 7906b26411..a2c08fb4e7 100644
--- a/doomsday/client/src/render/rendersystem.cpp
+++ b/doomsday/client/src/render/rendersystem.cpp
@@ -90,10 +90,7 @@ uint Store::allocateVertices(uint count)
 DENG2_PIMPL(RenderSystem)
 {
     ModelRenderer models;
-
     SkyDrawable sky;
-    SkyDrawable::Animator skyAnimator;
-
     SettingsRegister settings;
     SettingsRegister appearanceSettings;
     ImageBank images;
@@ -222,9 +219,6 @@ DENG2_PIMPL(RenderSystem)
                 .define(SReg::IntCVar,   "rend-particle-visible-near", 0)
 
                 .define(SReg::FloatCVar, "rend-sky-distance", 1600);
-
-        skyAnimator.setSky(&sky);
-        sky.setAnimator(&skyAnimator);
     }
 
     /**
diff --git a/doomsday/client/src/render/skydrawable.cpp b/doomsday/client/src/render/skydrawable.cpp
index 6bb2f29ac7..fc44f1c1dd 100644
--- a/doomsday/client/src/render/skydrawable.cpp
+++ b/doomsday/client/src/render/skydrawable.cpp
@@ -165,7 +165,7 @@ static void makeHemisphere(float height, float horizonOffset)
     }
 }
 
-static void rebuildHemisphereIfNeeded(Sky &sky)
+static void rebuildHemisphereIfNeeded(Sky const &sky)
 {
     static bool firstBuild = true;
     static float oldHorizonOffset;
@@ -191,7 +191,7 @@ static void rebuildHemisphereIfNeeded(Sky &sky)
     makeHemisphere(sky.height(), sky.horizonOffset());
 }
 
-static void configureSphereDrawState(Sky &sky, int layerIndex, hemispherecap_t setupCap)
+static void configureSphereDrawState(Sky const &sky, int layerIndex, hemispherecap_t setupCap)
 {
     // Default state is no texture and no fadeout.
     ds.texSize = Vector2i();
@@ -261,7 +261,7 @@ static void configureSphereDrawState(Sky &sky, int layerIndex, hemispherecap_t s
 }
 
 /// @param flags  @ref skySphereRenderFlags
-static void drawHemisphere(Sky &sky, SphereComponentFlags flags)
+static void drawHemisphere(Sky const &sky, SphereComponentFlags flags)
 {
     int const firstLayer = sky.firstActiveLayer();
     DENG2_ASSERT(firstLayer >= 0);
@@ -360,24 +360,20 @@ using namespace ::internal;
 
 DENG2_PIMPL(SkyDrawable)
 {
-    Animator *animator = nullptr;
-
-    ModelInfo models[MAX_SKY_MODELS];
+    ModelData models[MAX_SKY_MODELS];
     bool haveModels       = false;
     bool alwaysDrawSphere = false;
 
-    Sky *sky = 0;
-
     Instance(Public *i) : Base(i)
     {
         de::zap(models);
     }
 
-    inline ResourceSystem &resSys() {
+    static inline ResourceSystem &resSys() {
         return ClientApp::resourceSystem();
     }
 
-    void drawSphere()
+    void drawSphere(Sky const &sky) const
     {
         if(haveModels && !alwaysDrawSphere) return;
 
@@ -395,8 +391,8 @@ DENG2_PIMPL(SkyDrawable)
         glScalef(skyDistance, skyDistance, skyDistance);
 
         // Always draw both hemispheres.
-        drawHemisphere(self.sky(), LowerHemisphere);
-        drawHemisphere(self.sky(), UpperHemisphere);
+        drawHemisphere(sky, LowerHemisphere);
+        drawHemisphere(sky, UpperHemisphere);
 
         glMatrixMode(GL_MODELVIEW);
         glPopMatrix();
@@ -408,7 +404,7 @@ DENG2_PIMPL(SkyDrawable)
         glEnable(GL_DEPTH_TEST);
     }
 
-    void drawModels()
+    void drawModels(Sky const &sky) const
     {
         if(!haveModels) return;
 
@@ -424,13 +420,13 @@ DENG2_PIMPL(SkyDrawable)
 
         for(int i = 0; i < MAX_SKY_MODELS; ++i)
         {
-            ModelInfo &minfo          = models[i];
-            Record const *skyModelDef = minfo.def;
+            ModelData const &mdata    = models[i];
+            Record const *skyModelDef = mdata.def;
 
             if(!skyModelDef) continue;
 
             // If the associated sky layer is not active then the model won't be drawn.
-            if(!sky->layer(skyModelDef->geti("layer")).isActive())
+            if(!sky.layer(skyModelDef->geti("layer")).isActive())
             {
                 continue;
             }
@@ -442,16 +438,16 @@ DENG2_PIMPL(SkyDrawable)
             vis.pose.distance        = 1;
 
             Vector2f rotate(skyModelDef->get("rotate"));
-            vis.pose.yaw             = minfo.yaw;
+            vis.pose.yaw             = mdata.yaw;
             vis.pose.extraYawAngle   = vis.pose.yawAngleOffset   = rotate.x;
             vis.pose.extraPitchAngle = vis.pose.pitchAngleOffset = rotate.y;
 
             drawmodelparams_t &visModel = *VS_MODEL(&vis);
-            visModel.inter                       = (minfo.maxTimer > 0 ? minfo.timer / float(minfo.maxTimer) : 0);
-            visModel.mf                          = minfo.model;
+            visModel.inter                       = (mdata.maxTimer > 0 ? mdata.timer / float(mdata.maxTimer) : 0);
+            visModel.mf                          = mdata.model;
             visModel.alwaysInterpolate           = true;
             visModel.shineTranslateWithViewerPos = true;
-            App_ResourceSystem().setModelDefFrame(*minfo.model, minfo.frame);
+            resSys().setModelDefFrame(*mdata.model, mdata.frame);
 
             vis.light.ambientColor = Vector4f(skyModelDef->get("color"), 1);
 
@@ -485,13 +481,13 @@ void SkyDrawable::setupModels(defn::Sky const &def)
     for(int i = 0; i < def.modelCount(); ++i)
     {
         Record const &modef = def.model(i);
-        ModelInfo *minfo = &d->models[i];
+        ModelData *mdata = &d->models[i];
 
         // Is the model ID set?
         try
         {
-            minfo->model = &App_ResourceSystem().modelDef(modef.gets("id"));
-            if(!minfo->model->subCount())
+            mdata->model = &d->resSys().modelDef(modef.gets("id"));
+            if(!mdata->model->subCount())
             {
                 continue;
             }
@@ -499,10 +495,10 @@ void SkyDrawable::setupModels(defn::Sky const &def)
             // There is a model here.
             d->haveModels = true;
 
-            minfo->def      = modef.accessedRecordPtr();
-            minfo->maxTimer = int(TICSPERSEC * modef.getf("frameInterval"));
-            minfo->yaw      = modef.getf("yaw");
-            minfo->frame    = minfo->model->subModelDef(0).frame;
+            mdata->def      = modef.accessedRecordPtr();
+            mdata->maxTimer = int(TICSPERSEC * modef.getf("frameInterval"));
+            mdata->yaw      = modef.getf("yaw");
+            mdata->frame    = mdata->model->subModelDef(0).frame;
         }
         catch(ResourceSystem::MissingModelDefError const &)
         {} // Ignore this error.
@@ -514,7 +510,7 @@ bool SkyDrawable::hasModel(int index) const
     return (index >= 0 && index < MAX_SKY_MODELS);
 }
 
-SkyDrawable::ModelInfo &SkyDrawable::model(int index)
+SkyDrawable::ModelData &SkyDrawable::model(int index)
 {
     if(hasModel(index))
     {
@@ -524,16 +520,18 @@ SkyDrawable::ModelInfo &SkyDrawable::model(int index)
     throw MissingModelError("SkyDrawable::model", "Invalid model index #" + String::number(index) + ".");
 }
 
-SkyDrawable::ModelInfo const &SkyDrawable::model(int index) const
+SkyDrawable::ModelData const &SkyDrawable::model(int index) const
 {
-    return const_cast<ModelInfo const &>(const_cast<SkyDrawable *>(this)->model(index));
+    return const_cast<ModelData const &>(const_cast<SkyDrawable *>(this)->model(index));
 }
 
-void SkyDrawable::cacheDrawableAssets()
+void SkyDrawable::cacheDrawableAssets(Sky const *sky)
 {
+    DENG2_ASSERT(sky);
+
     for(int i = 0; i < MAX_SKY_LAYERS; ++i)
     {
-        Sky::Layer const &lyr = sky().layer(i);
+        Sky::Layer const &lyr = sky->layer(i);
         if(Material *mat = lyr.material())
         {
             d->resSys().cache(*mat, layerMaterialSpec(lyr.isMasked()));
@@ -544,61 +542,34 @@ void SkyDrawable::cacheDrawableAssets()
     {
         for(int i = 0; i < MAX_SKY_MODELS; ++i)
         {
-            ModelInfo &minfo = d->models[i];
-            if(!minfo.def) continue;
+            ModelData &mdata = d->models[i];
+            if(!mdata.def) continue;
 
-            d->resSys().cache(minfo.model);
+            d->resSys().cache(mdata.model);
         }
     }
 }
 
-void SkyDrawable::draw()
+void SkyDrawable::draw(Sky const *sky) const
 {
-    DENG_ASSERT_IN_MAIN_THREAD();
+    DENG2_ASSERT(sky);
+    DENG2_ASSERT_IN_MAIN_THREAD();
     DENG_ASSERT_GL_CONTEXT_ACTIVE();
 
     // The sky is only drawn when at least one layer is active.
-    if(sky().firstActiveLayer() < 0) return;
+    if(sky->firstActiveLayer() < 0) return;
 
     if(usingFog) glEnable(GL_FOG);
 
-    d->drawSphere();
-    d->drawModels();
+    d->drawSphere(*sky);
+    d->drawModels(*sky);
 
     if(usingFog) glDisable(GL_FOG);
 }
 
-bool SkyDrawable::hasAnimator() const
-{
-    return d->animator != 0;
-}
-
-void SkyDrawable::setAnimator(Animator *newAnimator)
-{
-    d->animator = newAnimator;
-}
-
-SkyDrawable::Animator &SkyDrawable::animator()
-{
-    if(d->animator) return *d->animator;
-    /// @throw MissingAnimatorError  No animator is presently configured.
-    throw MissingAnimatorError("SkyDrawable::animator", "Missing animator");
-}
-
-void SkyDrawable::setSky(Sky *sky)
-{
-    d->sky = sky;
-}
-
-Sky &SkyDrawable::sky()
-{
-    DENG2_ASSERT(d->sky);
-    return *d->sky;
-}
-
 MaterialVariantSpec const &SkyDrawable::layerMaterialSpec(bool masked) // static
 {
-    return ClientApp::resourceSystem()
+    return Instance::resSys()
                 .materialSpec(SkySphereContext, TSF_NO_COMPRESSION | (masked? TSF_ZEROMASK : 0),
                               0, 0, 0, GL_REPEAT, GL_CLAMP_TO_EDGE,
                               0, -1, -1, false, true, false, false);
@@ -665,20 +636,20 @@ void SkyDrawable::Animator::advanceTime(timespan_t /*elapsed*/)
     // Animate models.
     for(int i = 0; i < MAX_SKY_MODELS; ++i)
     {
-        ModelInfo &minfo = sky().model(i);
-        if(!minfo.def) continue;
+        ModelData &mdata = sky().model(i);
+        if(!mdata.def) continue;
 
         // Rotate the model.
-        minfo.yaw += minfo.def->getf("yawSpeed") / TICSPERSEC;
+        mdata.yaw += mdata.def->getf("yawSpeed") / TICSPERSEC;
 
         // Is it time to advance to the next frame?
-        if(minfo.maxTimer > 0 && ++minfo.timer >= minfo.maxTimer)
+        if(mdata.maxTimer > 0 && ++mdata.timer >= mdata.maxTimer)
         {
-            minfo.frame++;
-            minfo.timer = 0;
+            mdata.frame++;
+            mdata.timer = 0;
 
             // Execute a console command?
-            String const execute = minfo.def->gets("execute");
+            String const execute = mdata.def->gets("execute");
             if(!execute.isEmpty())
             {
                 Con_Execute(CMDS_SCRIPT, execute.toUtf8().constData(), true, false);
diff --git a/doomsday/client/src/render/viewports.cpp b/doomsday/client/src/render/viewports.cpp
index 2c29d07a49..908c639690 100644
--- a/doomsday/client/src/render/viewports.cpp
+++ b/doomsday/client/src/render/viewports.cpp
@@ -1157,7 +1157,7 @@ DENG_EXTERN_C void R_SkyParams(int layerIndex, int param, void * /*data*/)
         return;
     }
 
-    Sky &sky = ClientApp::renderSystem().sky().sky();
+    Sky &sky = ClientApp::worldSystem().map().sky();
     if(sky.hasLayer(layerIndex))
     {
         Sky::Layer &layer = sky.layer(layerIndex);
diff --git a/doomsday/client/src/world/p_ticker.cpp b/doomsday/client/src/world/p_ticker.cpp
index f05e25c879..80e931df0c 100644
--- a/doomsday/client/src/world/p_ticker.cpp
+++ b/doomsday/client/src/world/p_ticker.cpp
@@ -18,6 +18,8 @@
  */
 
 #include "de_base.h"
+#include "world/p_ticker.h"
+
 #include "de_network.h"
 #include "de_render.h"
 #include "de_play.h"
@@ -28,7 +30,6 @@
 #  include "render/skydrawable.h"
 #endif
 #include "world/map.h"
-#include "world/thinkers.h"
 #include "world/sky.h"
 
 using namespace de;
@@ -118,23 +119,8 @@ static void materialsTicker(timespan_t elapsed)
 void P_Ticker(timespan_t elapsed)
 {
     P_ControlTicker(elapsed);
-
 #ifdef __CLIENT__
     materialsTicker(elapsed);
-
-    SkyDrawable &sky = ClientApp::renderSystem().sky();
-    if(sky.hasAnimator())
-    {
-        sky.animator().advanceTime(elapsed);
-    }
 #endif
-
-    if(App_WorldSystem().hasMap() && DD_IsSharpTick())
-    {
-        Map &map = App_WorldSystem().map();
-
-        // Check all mobjs (always public).
-        map.thinkers().iterate(reinterpret_cast<thinkfunc_t>(gx.MobjThinker), 0x1,
-                               P_MobjTicker);
-    }
+    App_WorldSystem().tick(elapsed);
 }
diff --git a/doomsday/client/src/world/worldsystem.cpp b/doomsday/client/src/world/worldsystem.cpp
index 41fc21523d..36d0847de9 100644
--- a/doomsday/client/src/world/worldsystem.cpp
+++ b/doomsday/client/src/world/worldsystem.cpp
@@ -62,6 +62,7 @@
 #  include "server/sv_pool.h"
 #endif
 
+#include "world/p_ticker.h"
 #include "world/sky.h"
 #include "world/thinkers.h"
 
@@ -288,6 +289,7 @@ DENG2_PIMPL(WorldSystem)
     timespan_t time = 0;         ///< World-wide time.
 #ifdef __CLIENT__
     std::unique_ptr<Hand> hand;  ///< For map editing/manipulation.
+    SkyDrawable::Animator skyAnimator;
 #endif
 
     Instance(Public *i) : Base(i)
@@ -495,7 +497,7 @@ DENG2_PIMPL(WorldSystem)
 
 #ifdef __CLIENT__
         // Set up the SkyDrawable to get its config from the map's Sky.
-        ClientApp::renderSystem().sky().setSky(&map->sky());
+        skyAnimator.setSky(&ClientApp::renderSystem().sky());
 
         // Reconfigure the sky.
         defn::Sky skyDef;
@@ -882,6 +884,22 @@ timespan_t WorldSystem::time() const
     return d->time;
 }
 
+void WorldSystem::tick(timespan_t elapsed)
+{
+#ifdef __CLIENT__
+    d->skyAnimator.advanceTime(elapsed);
+#else
+    DENG2_UNUSED(elapsed);
+#endif
+
+    if(DD_IsSharpTick() && d->map)
+    {
+        // Check all mobjs (always public).
+        d->map->thinkers().iterate(reinterpret_cast<thinkfunc_t>(gx.MobjThinker), 0x1,
+                                   P_MobjTicker);
+    }
+}
+
 #ifdef __CLIENT__
 Hand &WorldSystem::hand(coord_t *distance) const
 {