anchor.diff:      (let* ((shoot-decision (mt19937:random 1d0)))
         (if (and (> (ammo secondary-weapon) 0) (< shoot-decision missile-chance))
           (missile enemy event)
  -        (shoot enemy (primary-weapon enemy) event)))))
  +        (shoot (primary-weapon enemy) event)))))
   
   (defmethod collide ((enemy enemy) event)
     (with-slots (parent offset size depth veloc health primary-weapon 
  
positive.code:    (ammo-refill-rate :initform 1)
     (ammo-deplete-rate :initform 1)))
  
  (defclass thopter (sprite collidable shooter direction-mixin)
    ((speed :initform 8)
     (timer :initform nil)
     (primary-weapon
  
negative.code:     :initform 4)
     (timer :initform 120)))
  
  (defclass enemy (mobile sprite collidable alarm)
    ((primary-weapon :accessor primary-weapon :initarg :primary-weapon)
     (secondary-weapon :accessor secondary-weapon :initarg :secondary-weapon)
     (timer :initform (+ 20 (mt19937:random 10) (mt19937:random 10)))
  