| Adult Swim Games | United States | 2005 | — | 6 |
| Adventure International | United States | 1978 | — | 1 |
| Adventure Planning Service | Japan | August 27, 1988 | — | 1 |
| Adventure Soft | United Kingdom | 1983 | 3 | 2 |
| Aeria | Japan | October 30, 2002 | 1 | — |
| Aeria Games | United States | 2006 | — | 1 |
| Aerie Gaming Studios | United States | 2018 | 1 | 1 |
| Aerosoft | Germany | 1991 | — | 19 |
| Aesir Interactive | Germany | — | 3 | — |
| Aeternum Game Studios | Spain | 2019 | 2 | 2 |
| Aether Studios | United States | 2014 | 1 | — |
| Aethon Collective | United States | January 21, 2021 | 1 | 1 |
| Afil Games | Brazil | — | 1 | 6 |
| AFTERBURN | Poland | November 20, 2016 | 1 | 1 |
| Agate Studio | Indonesia | 2009 | 2 | — |
| Agatsuma Entertainment | Japan | — | — | — |
| AGE | Japan | June 12, 1995 | 2 | 2 |
| Ageia | United States | 2002 | — | — |
| Agenda | Japan | November 2, 1990 | 1 | — |
| Agens | Norway | September 6, 2005 | 1 | — |
| AGEod | France | 2005 | 6 | — |
| Agetec | United States | 1998 | — | 13 |
| Ahead Multimedia | Sweden | August 10, 1993 | 1 | 1 |
| Aicom | Japan | 1988 | 3 | 1 |
| Aidem Media | Poland | September 10, 1997 | 4 | 4 |
| Aiming | Japan | May 12, 2011 | 1 | — |
| Airship Syndicate | United States | 2014 | 2 | — |
| Akabeisoft2 | Japan | 2005 | 2 | 1 |
| Akatsuki Games | Japan | December 16, 2021 | 2 | 2 |
| Akatsuki Inc. | Japan | 2010 | — | 1 |
| Akella | Russia | 1993 | 9 | 32 |
| Aksys Games | United States | July 14, 2006 | — | 30 |
| Alawar Entertainment | Russia | 1999 | 19 | 136 |
| Alawar Premium | Russia | — | 1 | 4 |
| Albino Moose Games | United States | — | 1 | 1 |
| Alchemist | Japan | August 14, 1991 | — | 6 |
| ALcot | Japan | 2003 | 2 | 3 |
| Alda Games | Czech Republic | 2013 | — | 1 |
| Alfa System | Japan | 1988 | 14 | — |
| Aliasworlds Entertainment | Belarus | 2001 | 10 | — |
| AliceSoft | Japan | 1989 | 31 | 31 |
| Alien Pixel Studios | Romania | — | 1 | — |
| Alientrap | — | 2002 | 1 | — |
| Alike Studio | Spain | 2014 | 2 | 1 |
| Alim | Japan | March 22, 2013 | 3 | — |
| All in! Games | Poland | 2018 | 2 | 9 |
| Alligata Software Ltd. | United Kingdom | 1982 | — | 1 |
| Allods Team | Russia | 2006 | 3 | — |
| Allumer | Japan | February 1978 | 1 | 1 |
| Almost Human | Finland | 2011 | 2 | 2 |
| Alpha Dog Games | Canada | — | 2 | — |
| AlphaDream | Japan | January 12, 2000 | 5 | — |
| Altar Games | — | 1997 | 3 | — |
| Alternative Software | United Kingdom | 1985 | 2 | 5 |
| Altron | Japan | September 10, 1983 | 9 | 6 |
| Alvion | Japan | 1996 | 1 | — |
| Amada Printing | Japan | July 16, 1956 | 1 | 1 |
| Amanita Design | Czech Republic | 2003 | 2 | 5 |
| Amanotes | Singapore | 2014 | 2 | 2 |
| Amata K.K. | Japan | June 25, 2008 | 1 | 2 |
| Amaze Entertainment | United States | 1997 | 3 | — |
| Amazon | United States | July 5, 1994 | 1 | — |
| Ambiera | Austria | — | 3 | 3 |
| Ambrella | Japan | 1996 | 7 | — |
| Ambrosia Software | United States | August 18, 1993 | — | — |
| Amedio Co., Ltd. | Japan | October 30, 1998 | 1 | — |
| American Laser Games | United States | 1989 | — | 1 |
| Amsoft | United Kingdom | 1984 | — | 3 |
| Amusement Vision | Japan | 2000 | 6 | — |
| Amuze | Sweden | 1996 | 1 | — |
| Amzy | Japan | April 21, 2008 | 1 | 1 |
| Anarchy Enterprises | United States | 1994 | 2 | 2 |
| Anate Studio | Ukraine | — | 1 | — |
| Anchor Inc. | Japan | 1996 | 1 | 5 |
| Ancient | Japan | 1990 | 5 | 2 |
| Ancient Forge | Poland | — | 1 | — |
| Andamiro | South Korea | 1992 | — | 2 |
| Andrade Games | Germany | — | 2 | 1 |
| Angry Demon Studio | Sweden | — | 1 | — |
| Anic | South Korea | May 2013 | — | 1 |
| Anima Project | Spain | — | 1 | — |
| Animation Arts | Germany | — | 4 | — |
| Animation Magic | United States | 1992 | 3 | — |
| Anino Games | — | November 2001 | 2 | — |
| Aniplex | Japan | September 1995 | — | 5 |
| Aniware AB | Sweden | 1992 | 1 | — |
| Ankama | France | June 2001 | 3 | 3 |
| Ankama Games | France | October 2, 2006 | 2 | 4 |
| Another Indie | Taiwan | — | — | 1 |
| Anshar Studios | Poland | 2012 | 3 | 2 |
| Ant Software | United States | 1989 | 3 | — |
| Ant Workshop | United Kingdom | — | — | 1 |
| Antimatter Games | United Kingdom | 2013 | 1 | — |
| Anuman | France | 2000 | 3 | 3 |
| Ape, Inc. | Japan | March 1989 | 1 | — |
| Apeiron | — | 2002 | 1 | — |
| Apex Computer Productions | United Kingdom | — | 2 | — |
| APh Technological Consulting | United States | 1974 | 4 | — |
| Apogee Entertainment | — | 2008 | — | 3 |
| Apogee Software | United States | — | 8 | 9 |