anchor.diff:    (with-slots (parent offset size depth veloc) missile
       (when (and parent (or (and (typep missile 'missile)
   			       (typep (event-hit event) 'enemy))
  -                          (typep (event-hit event) 'explosion)
  -			  (and (typep missile 'enemy-missile)
  -			       (typep (event-hit event) 'thopter))))
  +                          (typep (event-hit event) 'explosion)))
  +      (let ((explosion (make-instance 'anim :name :explosion)))
  +        (make-instance 'explosion :parent parent
  +                       :offset (+ offset (/ size 2) (/ (size explosion) -2))
  +                       :depth depth :veloc (/ veloc 2)
  +                       :image explosion
  +                       :timer 10))
  +      (detach parent missile))))
  +
  +(defmethod collide ((missile enemy-missile) event)
  +  (with-slots (parent offset size depth veloc) missile
  +    (when (and parent 	  (and (typep missile 'enemy-missile)
  +			       (typep (event-hit event) 'thopter)))
         (let ((explosion (make-instance 'anim :name :explosion)))
           (make-instance 'explosion :parent parent
                          :offset (+ offset (/ size 2) (/ (size explosion) -2))
  
positive.code:                        :offset (complex (/ (x size) 2) (* (y size) 3/4))
                         :image (make-instance 'anim :name :thopter)
                         :health 4 :firepower 3 :missiles 2)))
           (subscribe (game-keys game) thopter)))
        ((:server :client)
          (let ((thopter1 (make-instance
  
negative.code:    (health :initform 100)
     (veloc-scale :initform 0.5d0)
     (ignore-objects :initform t)
     (fire-rate :initform 2)
     (missiles :initform 2)))
  
  (defclass enemy-bullet (sprite mobile collidable alarm)
    ((timer :initform 60)
  