Putting a time delay on user input

I'm interested in creating Snake using autolisp, but as far as I can tell, user input is required to get past a grread command. Is there anyway I can break the grread command if no input is received within amount of time?

I believe that I am understanding you correctly that you have grread setup with tracking. If the user does not move the mouse the code stays on grread.

I haven't found a way to get past this.

You used to be able to supply continuous input to the grread function by including an expression to regenerate the drawing within the grread expression - though, this is not recommended.

Here is an example to demonstrate:

(defun c:tg2 ( / o p ) 
   (setq p (getvar 'viewctr))
   (setq o
       (vla-addcircle (vla-get-modelspace (vla-get-activedocument (vlax-get-acad-object)))
           (vlax-3D-point (cons (+ (car p) (/ (getvar 'viewsize) 5.0)) (cdr p)))
           (/ (getvar 'viewsize) 20.0)
       )
   )
   (setq p (vlax-3D-point p))
   (while (= 5 (car (grread t 14 1)))
       (vla-rotate o p 0.0175)
       (command "_.regen")
   )
   (princ)
)
(vl-load-com) (princ)