There was a project called Pelzkus Pro Skater, made by gOmO_3. http://www.coniserver.net/ubbthreads/showthreaded.php/Cat/0/Number/657519/page/0
By the way it inspired me to continue, when i was about to give up, thinking that it is impossible to create this kind of game in GS.Thank you, gOmO_3!