“Garry’s Mod” is a fairly popular modification add-on to the first-person shooter game Half-Life 2. Garry’s Mod doesn’t actually contribute any benefits to the game play, but it allows Half-Life 2 players or enthusiasts to modify objects and/or features in the Source engine, which is the 3-D gaming engine used to run Half-Life 2. Lua scripting has also been added to Garry’s Mod to allow players to create personalized game modes and weaponry. Of course, along with the introduction of Lua scripting support to Garry's Mod comes the predictable appearance of Garry's Mod-specific Lua viruses. So far, all of them simply copy themselves into a specific location and add a reference to themselves in the startup list.
Corresponding with the appearance of the virus scripts was the appearance of antivirus scripts. Unfortunately, some of those antivirus scripts are themselves viruses—the classic and misguided "spread to all infected machines and remove from them everything virus-like, other than me." The problem is that bugs in the spreading process and the resulting network load, along with running unsolicited code on uncontrolled machines, is both unethical and even illegal in some countries.
There's always someone who thinks it's a good idea. I will keep you posted on any further developments with these issues.