Half-Life easter eggs discovered in CounterStrike: Global Offensive beta textures
Players of CounterStrike have stumbled upon some Half-Life easter eggs in the closed beta vpk files.
Several textures have been found found which are intended for whiteboards. The writing on them jokes about the game development process and make several references to the Half-Life series.
Many of the references are obvious, with several Half-Life characters mentioned including Gordon, Eli, Dr. Breen and Barney Calhoun. The crowbar poster with the name “Raising the Bar” is a direct reference to the book which Valve released detailing the HL2 development process. Blue Mesa Airlines is a subtle hint to Black Mesa from the first game. There are also references to Valve's notorious delays and the massive amount of crates that always appear in Valve games.
Try not to get too excited, these are most likely just the artists having a bit of fun while developing the game.
Source: counterstrikego.com
