Back in high school I would try to play CS 1.6 on the library computers. The librarians had access to screen viewing software on all computers in the library and quickly caught me every time.

I played around with visual studio C# and created an application that would continuously monitor running applications (every X ms), detect when a specified .exe was found, and either (1) constantly kill it, (2) display a message, or (3) run a different .exe.

Never quite got to s1mple's level, but I did play a good amount of CS after that!