Half-Life (13 sept. 1998 – 13 sept. 2006)
Description:
 Half-Life (1998)
Half-Life: Opposing Force (1999)
Half-Life: Blue Shift (2001)
Half-Life 2 (2004)
Half-Life 2: Episode One (2006) 
Ajouté au bande de temps:
Date:
13 sept. 1998
13 sept. 2006
 ~ 8 years