Half-Life: Blue Shift

==Guard Duty (pre-release)==
Guard duty trailer logo.png|Early trailer version
This can be found in 640logos.spr in the final game's files.
==2001==
Category:Valve Corporation
Category:Half-Life
Category:Video games
Category:Windows games
Category:MacOS games
Category:Linux games
Category:First-person shooters
Category:Science fiction video games
Category:Video games released in 2001
Category:2001
Category:2000s video games