| Appaloosa Interactive | United States | 1993 | 3 | — |
| Appeal | Belgium | 1995 | 1 | — |
| Appelmoes | Netherlands | — | 1 | — |
| Apple Inc. | United States | April 1976 | — | — |
| Applibot | Japan | July 7, 2010 | 2 | — |
| Application Systems Heidelberg | Germany | 1985 | — | 4 |
| AppSir | Philippines | — | 4 | 4 |
| APriori Digital | United Kingdom | June 28, 2013 | 2 | 2 |
| Apus Software | Belarus | 2005 | 4 | 4 |
| AQ Interactive | Japan | October 2005 | 1 | 4 |
| Aqua Pacific | United Kingdom | 1999 | 2 | — |
| Aquaplus | Japan | October 1994 | 5 | 7 |
| Aquiris Game Studio | Brazil | 2007 | 3 | 2 |
| Aquria | Japan | January 8, 2002 | 3 | — |
| Arario Corporation | Japan | June 2007 | — | 1 |
| Arc Developments | United Kingdom | 1984 | 1 | — |
| Arc Games | United States | 2008 | — | 3 |
| Arc System Works | Japan | May 12, 1988 | 51 | 45 |
| Arcadia Project | Japan | August 2002 | 1 | — |
| Arcen Games | United States | 2009 | 2 | 1 |
| ArenaNet | United States | 2000 | 4 | — |
| Argonaut Games | United Kingdom | 1982 | 7 | — |
| Aria | Japan | March 2006 | — | 1 |
| Ariel Co., Limited | Taiwan | November 28, 2017 | — | 2 |
| Arika | Japan | November 1995 | 18 | — |
| Ariolasoft | Germany | 1982 | 2 | 1 |
| Ariolasoft UK | United Kingdom | — | — | 2 |
| Arise | Belarus | 2002 | 1 | — |
| Arkadium | United States | 2001 | 1 | — |
| Arkane Studios | France | 1999 | 8 | — |
| Armor Games | United States | October 2005 | 1 | 3 |
| Armor Games Studios | United States | — | — | 15 |
| Arrowiz | People's Republic of China | 2016 | 2 | — |
| Art & Magic | Belgium | 1991 | 4 | 3 |
| Art Co., Ltd | Japan | 1995 | 3 | — |
| Art Games Studio | Poland | — | 5 | 10 |
| Artdink | Japan | April 21, 1986 | 31 | 13 |
| Arte | Germany | — | — | 1 |
| Arte France | France | June 2, 1986 | 1 | 2 |
| Artech Digital Entertainment | Canada | 1982 | 3 | — |
| Artefacts Studio | France | 1994 | 1 | — |
| ArtePiazza | Japan | November 1989 | 2 | — |
| Artic Software | United Kingdom | — | 1 | 2 |
| ArticNet | Japan | April 4, 2013 | 2 | — |
| Artifex Mundi | Poland | 2006 | 14 | 70 |
| Artificial Life, Inc. | — | 1994 | 1 | — |
| Artisan Studios | Canada | 2016 | 2 | — |
| Artland | Japan | September 14, 1978 | — | — |
| Artoon | Japan | August 27, 1999 | 5 | — |
| Artplant | Norway | 2001 | 2 | — |
| Aruma Studios | Spain | — | 1 | — |
| Arush Entertainment | United States | — | — | 1 |
| Arxel Tribe | — | 1990 | 1 | — |
| Arzest | Japan | June 25, 2010 | 4 | — |
| ASa Project | Japan | March 30, 2007 | 2 | 2 |
| Ascaron | Germany | 1991 | 12 | 4 |
| Ascendant Studios | United States | 2018 | 1 | — |
| ASCII Corporation | Japan | June 24, 1991 | 3 | 12 |
| ASCII Media Works | Japan | April 2008 | 1 | 1 |
| Ashborne Games | Czech Republic | 2020 | 1 | — |
| ASK | Japan | 1972 | — | 1 |
| ASK Kodansha Co., Ltd. | Japan | November 26, 1981 | 2 | 2 |
| Asmik Ace Entertainment | Japan | 1985 | 6 | 12 |
| Asobo Studio | France | October 17, 2002 | 6 | — |
| Aspect | Japan | March 25, 1991 | 14 | — |
| Asphere Innovations | Thailand | 2001 | — | 1 |
| Aspyr | United States | 1996 | 11 | 21 |
| Assemble Entertainment | Germany | 2016 | — | 11 |
| Asteristic Game Studio | Brazil | — | 1 | 1 |
| Astragon | Germany | 2000 | 2 | 16 |
| Astrotale Games | Bosnia and Herzegovina | 2019 | 1 | — |
| Asylum Entertainment | United States | 2001 | 2 | — |
| Asylum Square | Germany | — | 3 | 3 |
| Atari | United States | June 27, 1972 | 11 | 84 |
| Atari Corporation | United States | July 2, 1984 | — | 3 |
| Atari Games | United States | July 1984 | 13 | 9 |
| Atari Interactive | United States | 1998 | — | 1 |
| Atari Program Exchange | United States | February 1981 | — | 1 |
| Atari SA | France | June 1983 | 1 | 11 |
| Atari, Inc. | United States | February 1993 | — | 24 |
| Atari, Inc. | United States | February 1993 | 1 | 17 |
| Atari, Inc. | United States | June 27, 1972 | 22 | 23 |
| Atarisoft | United States | 1983 | — | 1 |
| Atelier 801 | France | October 14, 2011 | 1 | 1 |
| Athena | Japan | July 1987 | 5 | 3 |
| Atlantis Interactive Entertainment | France | 2003 | 2 | 1 |
| Atlus | United States | April 7, 1986 | 1 | — |
| Atomic Games | United States | 1989 | 5 | — |
| Atomic Planet Entertainment | United Kingdom | 2000 | 2 | — |
| Atomic Raccoon Studio | France | — | 1 | 1 |
| AtomicTorch Studio | Singapore | — | 1 | 1 |
| Attention to Detail | United Kingdom | 1988 | 3 | — |
| Attic Entertainment Software | Germany | September 1990 | 3 | — |
| Atypique Studio | France | June 27, 2017 | 1 | 1 |
| Audiogenic | United Kingdom | 1985 | 3 | — |
| August | Japan | 2001 | 3 | 3 |
| Auroch Digital | United Kingdom | — | 7 | 1 |
| Aurogon Shanghai | People's Republic of China | September 28, 2007 | 4 | 1 |
| Aurora Punks | Sweden | — | — | 2 |
| Autobótika | Colombia | — | 1 | — |