Colors and identity In Half-Life, orange represents science, survival, and Gordon Freeman's resistance in the midst of the scientific chaos of Black Mesa. In Opposing Force green signals action, containment and conflict, underscoring the military nature of Adrian Shephard's campaign. In Blue Shift with its characteristic blue it evokes security, surveillance and protection, following the story of guard Barney Calhoun. Finally, Decay turns red, symbolizing the emergency, danger and collaboration …