anchor.diff:  (defmethod alarm ((wave wave-controller) event)
     (with-slots (level) wave
       (incf level)
  -    (spawn-wave (+ 2 level))))
  +    (spawn-wave level (+ 2 level))))
   
   ;; For interactive use:
   (defun thopter ()
  
positive.code:                          :health 4 :firepower 3 :missiles 1)))
            (subscribe (game-keys game) thopter1)
            (subscribe (game-keys game) thopter2))))
      (spawn-wave (+ 2 (level (game-wave game))))))
  
  (defmethod game-update :after ((game thopter-game))
    (let* ((thopter (iter (for i in-vector (children (game-root game)))
  
negative.code:     (detach (parent bullet) bullet)))
  
  (defmethod update ((enemy enemy) event)
    (with-slots (parent (xy offset) (v veloc) (s size) accel health difficulty)
        enemy
      (labels
          ((circular (r)
             (+ ;; circular motion
  