anchor.diff:          (change-key :cleared-lines (lambda (x) (+ x cleared-lines))))))
   
   (defun inc-level (game)
  -  (with game :level (1+ (truncate (@ game :cleared-lines) 10))))
  +  (with game :level (truncate (@ game :cleared-lines) 10)))
   
   (defun update-keys-down (game incoming-keys-down)
     (with game :keys-down
  
positive.code:       (:drop-counter 0)
        (:state :active)
        (:cleared-lines 0)
        (:level 1)
        (:keys-down (fset:map))
        (:rng (make-functional-rng)) |})
  
  
negative.code:     (draw-string "GAME OVER" 30 60)))
  
  (defun drop-counter-reset (game)
    (with game :drop-counter (max 6 (- 30 (* 2 (@ game :level))))))
  
  (defun legal-block-position (game fb)
    (let* ((main-grid (@ game :main-grid)))
  