If you're among the many Garry's Mod users experiencing the startup error "Unable to shade polygon normals," you should probably keep that information to yourself. According to GMod creator Garry Newman, he introduced the error this week and it's designed to only appear on illegal copies of the game as a means of flushing out pirates.
Upon receiving the error, unsuspecting pirates posted on the Steam forum looking for assistance. Those individuals are being banned from the message board. Making the situation even more interesting, the polygon error message is followed by a number in parenthesis that most folks would associate with an error code. See the example below:
"Engine Error:Unable to shade polygon normals(#################)"
The kicker is, that's actually a SteamID, so pirates are unknowingly revealing their Steam identity. Speaking with Bit-Gamer, the developer claimed that 2,500 pirates were identified 15 hours after rolling out the error. Newman doesn't have the power to ban Steam IDs and it's unclear if any accounts have been banned outside of the forum.
Instead, he wants this to serves as a point of humiliation for people running illegitimate copies of the game. "I did this for the people that did buy Garry's Mod. They get to point and laugh at pirates. If we leave it easy for people to pirate we're betraying the people that paid," Newman said. "I'm just having fun at the pirates expense."