Early on Tuesday the stocks of several gaming companies, Tencent among them, fell sharply by up to 11% at Hong Kong markets, after the Propaganda Department of China's Communist Party announced at the ChinaJoy expo that video games needed to be "good, clean and secure". Shares of companies like Tencent, NetEase and XD started tumbling in response. The shares of China Mobile Games and Entertainment Group (CMGE) even fell by a whopping 20%. Several gaming companies from elsewhere in Asia,…