anchor.diff:    (with-slots (parent offset size veloc timer missiles fire-rate) enemy
       (setf timer
             (ceiling (+ 5 (mt19937:random 30) (mt19937:random 30)) fire-rate))
  -    (if (> missiles 0) 
  +    (let* ((shoot-decision (mt19937:random 1d0)))
  +      (if (and (> missiles 0) (> shoot-decision 0.7))
   	(progn (decf missiles) 
   	       (make-instance
   		'enemy-missile
   		:parent parent 
  -		:offset (+ offset (/ size 2) )
  +		:offset (+ offset (complex (/ (x size) 2) (y size)))
   		:depth -1
   		:veloc veloc
   		:image (make-instance 'image :name :enemy-missile-s)))
  -	(shoot enemy event))))
  +	(shoot enemy event)))))
   
   (defmethod collide ((enemy enemy) event)
     (with-slots (parent offset size depth veloc health firepower missiles) enemy
  
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)
  