The traditional target of computer game security is mainly copy protection. The emergence of online games fundamentally changes the security requirements for computer games. Although computer game development often utilizes cutting edge technology in computer graphics, artificial intelligence, human computer interaction and programming, game providers (developers or operators) do not pay much attention to security techniques. In this paper, we look into security failures that have happened or might happen in online games, and discuss some key security issues that have to concern online game providers. Specifically, we look into various kinds of online cheating, and introduce security techniques to deal with cheating prevention, though meanwhile other security issues are also discussed. - See more at: http://0-www.emeraldinsight.com.library.ada.edu.az/journals.htm?issn=0264-0473&volume=20&issue=2&articleid=861958&show=abstract#sthash.XXOOoAMl.dpuf