User blog comment:Argorrath/Ghosts Title Update 1.28.14/@comment-1854594-20140129003930/@comment-3967954-20140129074304

Technically, they're not even ripping off Counter-Strike, since Gun Game was never one of the default gametypes in either CS or CS:S. It was a player-created mod that was never copyrighted and appeared in several games subsequent. The end.