diff --git a/client/src/arena.lisp b/client/src/arena.lisp
index 2cca73f..eb73bd3 100644
--- a/client/src/arena.lisp
+++ b/client/src/arena.lisp
@@ -58,11 +58,13 @@
 
 
 (defun shoot-ball (player)
-  (let ((pos (position-of player)))
+  (let ((pos (position-of player))
+        (gaze (gaze-of player)))
     (run (>> (assembly-flow 'ball-model
                             :owner player
-                            :position (vec3 (+ (x pos) 1.0) 10.0 (- (y pos)))
-                            :force (mult (gaze-of player) 20000))
+                            ;; fixme: translate by +x to center ball at mortar
+                            :position (vec3 (x pos) 8.2 (- (y pos)))
+                            :force (mult gaze 20000))
              (-> ((mortar-combat)) (ball)
                (let ((group (find-node (root-of (scene-of *system*)) :ball-group)))
                  (adopt group ball)))))))
diff --git a/client/src/main.lisp b/client/src/main.lisp
index e56dd5e..33a2a64 100644
--- a/client/src/main.lisp
+++ b/client/src/main.lisp
@@ -1,7 +1,7 @@
 (in-package :mortar-combat)
 
 
-(define-constant +framestep+ 0.017)
+(define-constant +world-step+ 0.016)
 (defvar *main-latch* (mt:make-latch))
 
 
@@ -212,22 +212,27 @@
                                        scenegraph-root))
                (let ((board (find-node (root-of scene) :ui)))
                  (make-ui board))
-               (let ((accumulated-time 0)
+               (let ((accumulated-packet-time 0)
+                     (accumulated-step-time 0)
                      start looped-flow)
                  (setf looped-flow
                        (>> (instantly ()
                              (setf start (real-time-seconds))
                              (let ((*system* this))
                                (drain task-queue))
-                             (when (> accumulated-time 0.05)
+                             (when (> accumulated-packet-time 0.05)
                                (send-client-data this)
                                (broadcast-arena-state this)
-                               (setf accumulated-time 0)))
+                               (setf accumulated-packet-time 0)))
                            (-> ((physics)) ()
-                             (observe-universe +framestep+))
+                             (when (> accumulated-step-time (- +world-step+ 0.02))
+                               (observe-universe +world-step+)
+                               (setf accumulated-step-time 0)))
                            (scene-processing-flow scene)
                            (instantly ()
-                             (incf accumulated-time (- (real-time-seconds) start))
+                             (let ((delta (- (real-time-seconds) start)))
+                               (incf accumulated-packet-time delta)
+                               (incf accumulated-step-time delta))
                              (when (enabledp this)
                                (run looped-flow)))))
                  (run looped-flow)))))))