by Head Games Publishing, Inc., 1996
by Rebellion Developments Ltd., 1999
by Monolith Productions, Inc., 2001
by Blizzard Entertainment Inc., 1994
by Sierra On-Line, Inc., 1995
by Apogee Software, Ltd., 1996
by Hypnotix, Inc., 1998
by Hypnotix, Inc., 1999
by NovaLogic, Inc., 1998
by NovaLogic, Inc., 1999
by Dynamix, Inc., 1989
by Tiertex Ltd., 1992
by id Software, Inc., 1993
by id Software, Inc., 1994
by Sunstorm Interactive, Inc., 1997
by 3D Realms Entertainment, Inc., 1996
by Rage Games Ltd., 1999
by DMA Design Limited, 1997
by Rockstar Canada, 1999
by Valve Corporation, 1998
by Gearbox Software LLC, 1999
by Raven Software Corporation, 1998
by Raven Software Corporation, 1997
by Illusion Softworks, a.s., 1999
by Rage Games Ltd., 2001
