| 14 Degrees East | March 3, 1999 | 2 | — |
| 17-BIT | 2009 | 1 | 1 |
| 1st Playable Productions | 2005 | 3 | — |
| 2015, Inc. | 1997 | 1 | — |
| 20th Century Studios | 1985 | — | 1 |
| 2K | January 25, 2005 | 1 | 72 |
| 2K Los Angeles | 2002 | 6 | — |
| 2K Marin | December 17, 2007 | 4 | — |
| 2K Play | September 10, 2007 | — | 8 |
| 2K Sports | January 25, 2005 | — | 44 |
| 38 Studios | 2006 | 2 | — |
| 3D Realms | 1994 | 6 | 13 |
| 3d6 Games | 1999 | 1 | — |
| 3Romans | — | 2 | — |
| 4mm Games | 2008 | 1 | — |
| 5th Cell | August 28, 2003 | 8 | — |
| 7th Level | April 28, 1993 | 4 | 2 |
| 8-Bit Legit | — | — | 3 |
| 989 Studios | 1995 | 11 | 10 |
| Absolute Entertainment | 1986 | — | 5 |
| Accelerate Games | — | — | 17 |
| Acclaim Games | January 6, 2006 | 1 | 2 |
| Acclaim Studios Austin | August 14, 1991 | 20 | — |
| Accolade | 1984 | 9 | 22 |
| Ackk Studios | 2013 | 1 | 1 |
| Activision Blizzard | July 10, 2008 | — | 3 |
| Activision Value Publishing | August 2000 | — | 5 |
| Adobe | February 28, 1982 | — | — |
| Adult Swim | September 1999 | 1 | — |
| Adult Swim Games | 2005 | — | 6 |
| Adventure International | 1978 | — | 1 |
| Aeria Games | 2006 | — | 1 |
| Aerie Gaming Studios | 2018 | 1 | 1 |
| Aether Studios | 2014 | 1 | — |
| Aethon Collective | January 21, 2021 | 1 | 1 |
| Ageia | 2002 | — | — |
| Agetec | 1998 | — | 13 |
| Airship Syndicate | 2014 | 2 | — |
| Aksys Games | July 14, 2006 | — | 30 |
| Albino Moose Games | — | 1 | 1 |
| Amaze Entertainment | 1997 | 3 | — |
| Amazon | July 5, 1994 | 1 | — |
| Ambrosia Software | August 18, 1993 | — | — |
| American Laser Games | 1989 | — | 1 |
| Anarchy Enterprises | 1994 | 2 | 2 |
| Animation Magic | 1992 | 3 | — |
| Ant Software | 1989 | 3 | — |
| APh Technological Consulting | 1974 | 4 | — |
| Apogee Software | — | 8 | 9 |
| Appaloosa Interactive | 1993 | 3 | — |
| Apple Inc. | April 1976 | — | — |
| Arc Games | 2008 | — | 3 |
| Arcen Games | 2009 | 2 | 1 |
| ArenaNet | 2000 | 4 | — |
| Arkadium | 2001 | 1 | — |
| Armor Games | October 2005 | 1 | 3 |
| Armor Games Studios | — | — | 15 |
| Arush Entertainment | — | — | 1 |
| Ascendant Studios | 2018 | 1 | — |
| Aspyr | 1996 | 11 | 21 |
| Asylum Entertainment | 2001 | 2 | — |
| Atari | June 27, 1972 | 11 | 84 |
| Atari Corporation | July 2, 1984 | — | 3 |
| Atari Games | July 1984 | 13 | 9 |
| Atari Interactive | 1998 | — | 1 |
| Atari Program Exchange | February 1981 | — | 1 |
| Atari, Inc. | February 1993 | — | 24 |
| Atari, Inc. | February 1993 | 1 | 17 |
| Atari, Inc. | June 27, 1972 | 22 | 23 |
| Atarisoft | 1983 | — | 1 |
| Atlus | April 7, 1986 | 1 | — |
| Atomic Games | 1989 | 5 | — |
| Autumn Games | 2007 | — | 2 |
| Avalanche Software | 1995 | 8 | — |
| Avalon Hill | 1958 | 4 | 9 |
| Axis Games | 2003 | 1 | 1 |
| Axol Studio, LLC | 2015 | 6 | 6 |
| Azeroth, Inc. | — | 1 | — |
| Babaroga | 2002 | 2 | — |
| Backbone Emeryville | 2003 | 1 | — |
| Backflip Studios | March 2009 | 1 | — |
| Bad Dream Games | — | 1 | — |
| BAM! Entertainment | October 7, 1999 | — | 5 |
| Basilisk Games | 2005 | 2 | 2 |
| Bay 12 Games | — | 1 | — |
| Bend Studio | 1994 | 11 | — |
| Bethesda Game Studios | 2001 | 6 | — |
| Bethesda Game Studios Dallas | — | 1 | — |
| Bethesda Softworks | 1986 | 10 | 53 |
| Beyond Games | 1992 | 1 | — |
| Big Ape Productions | 1997 | 1 | — |
| Big Finish Games | 2007 | — | — |
| Big Fish Games | 2002 | 12 | 68 |
| Big Huge Games | February 2000 | 2 | — |
| Bit Fry | November 2013 | 2 | 2 |
| Black Isle Studios | 1996 | 4 | 2 |
| Black Lantern Studios, Inc. | 2003 | 3 | — |
| Black Ops Entertainment | 1994 | 2 | — |
| Blaze | — | 1 | 2 |
| Blendo Games | 2010 | 1 | 1 |