I am not sure if the visa on arrival is available again right now, but it is impossible for the Asia Games. I still suggest you handle the China visa application(https://www.travelchinaguide.com/embassy/visa/application.htm) in advance in HK. That is safer. It can arrange it yourself in Commissioner office of China Foreign Ministory in Wanchai,HK. Or entrust a travel serive which can assure you to get it on the same day.