diff --git a/src/play_clj/core.clj b/src/play_clj/core.clj
index 94308b4..1cd401a 100644
--- a/src/play_clj/core.clj
+++ b/src/play_clj/core.clj
@@ -31,8 +31,6 @@
   [obj]
   {:type :actor :object obj})
 
-(defn- dummy [& args])
-
 (load "core_2d")
 (load "core_deprecated")
 (load "core_global")
@@ -42,18 +40,17 @@
 
 (defn defscreen*
   [{:keys [on-show on-render on-hide on-pause on-resize on-resume]
-    :or {on-show dummy on-render dummy on-hide dummy
-         on-pause dummy on-resize dummy on-resume dummy}
     :as options}]
   (let [screen (atom {})
         entities (atom '())
         execute-fn! (fn [func & {:keys [] :as options}]
-                      (let [entities-list @entities]
-                        (some->> (func (merge @screen options) entities-list)
-                                 list
-                                 flatten
-                                 (remove nil?)
-                                 (compare-and-set! entities entities-list))))
+                      (when func
+                        (let [entities-list @entities]
+                          (some->> (func (merge @screen options) entities-list)
+                                   list
+                                   flatten
+                                   (remove nil?)
+                                   (compare-and-set! entities entities-list)))))
         create-renderer-fn! #(swap! screen assoc :renderer (renderer %))
         update-fn! #(swap! screen merge %)]
     {:screen screen
@@ -83,10 +80,10 @@
      (defonce ~n (defscreen* fns#))))
 
 (defn defgame*
-  [{:keys [on-create] :or {on-create dummy}}]
+  [{:keys [on-create]}]
   (proxy [Game] []
     (create []
-      (on-create this))))
+      (when on-create (on-create this)))))
 
 (defmacro defgame
   [n & {:keys [] :as options}]
diff --git a/src/play_clj/core_global.clj b/src/play_clj/core_global.clj
index 00182f4..7f0b28e 100644
--- a/src/play_clj/core_global.clj
+++ b/src/play_clj/core_global.clj
@@ -45,11 +45,7 @@
 
 (defn- input-processor
   [{:keys [on-key-down on-key-typed on-key-up on-mouse-moved
-           on-scrolled on-touch-down on-touch-dragged on-touch-up]
-    :or {on-key-down dummy on-key-typed dummy
-         on-key-up dummy on-mouse-moved dummy
-         on-scrolled dummy on-touch-down dummy
-         on-touch-dragged dummy on-touch-up dummy}}
+           on-scrolled on-touch-down on-touch-dragged on-touch-up]}
    execute-fn!]
   (reify InputProcessor
     (keyDown [this k]
@@ -78,9 +74,7 @@
       false)))
 
 (defn- gesture-detector
-  [{:keys [on-fling on-long-press on-pan on-pan-stop on-pinch on-tap on-zoom]
-    :or {on-fling dummy on-long-press dummy on-pan dummy on-pan-stop dummy
-         on-pinch dummy on-tap dummy on-zoom dummy}}
+  [{:keys [on-fling on-long-press on-pan on-pan-stop on-pinch on-tap on-zoom]}
    execute-fn!]
   (let [listener
         (reify GestureDetector$GestureListener