not likely a virus, viruses do a great many strange things, but hiding a random game is not one of them. It is possible that someone is logging on and playing a stick prank on you (or it is intervention from an addiction lol). The other possibility is that you are experiencing the beginning of a HDD failure. Try some HDD recovery or testing software and see if that finds anything. Easeus makes some good free software for that.
Also, any possibility (however strange) that you are reloading an image from before you installed the game?
LOL, I hope you are not running that many anti-virus programs at once on your computer. Pick one antivirus (Microsoft Security Essentials), and one anti-malware (Malwarebytes until MSE v4 comes out) and stick with them. Running multiple AVs tends to cause issues of their own and can slow a system down way more than a virus ever will.