Garry's Mod now includes a deliberate error designed to identify and ban pirates.

Garry's Mod is currently priced at £6, meaning 2,500 pirates is equal to £15,000 in potential lost sales. ' I don't really look at it as lost revenue though, Garry told Bit-Gamer.

Although it first became popular in 2004 as a free download, Garry's Mod has been available on a Steam as an officially-licensed Source engine product since 2006.

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.