1. Companies starting with A:

      A Force More Powerful
      A2M
      Aardvark
      About.com
      Absolute Entertainment
      Absolutist Ltd.
      Access Software
      Acclaim Entertainment
      Accolade
      Accursed Toys
      ACMedia
      Acorn Software Products
      Action Forms
      Actionsoft
      Activision
      Actualize
      Addison-Wesley
      Adeline Software International
      Adrenal Rush
      Advanced Gaming Systems
      Advanced Operating Systems
      Adventure International
      Adventure World
      Aegis
      Affiliate Venture Publishing
      Agetec
      AHA! Software
      Aidsoft
      Airtight Games
      Akella
      Aksys
      Alawar Entertainment
      Alawar Five-BN
      Alawar Stargaze
      Aldorlea Games
      Aliasworlds
      Alpha Products
      ALTAR Games
      Amaranth Games
      Amaze Entertainment
      Amazing Media
      American Game Factory
      American Small Business Computers
      Amtel Vision
      Anarchy Enterprises
      Another Day
      Antic
      AOL
      Apeiron
      Apogee
      Apple Computer
      Applications Plus
      Applied Graphics Engineering
      Apus Software
      ArcadeStudio
      Arcadia
      Arc
      Archee
      ArenaNet
      Argo Games
      Arise
      Arrowsoft
      Artech
      Artifical Mind And Movement
      Artificial Life
      ARUSH
      Ascaron
      ASCII Entertainment Software
      Aspyr
      Astral Software
      Asus
      Asymmetric Publications
      Atari Program Exchange
      Atari
      ATD
      Aterdux Entertainment
      Atlus
      Australian Game Developers
      Automated Simulations
      Avalanche Studios
      Avalon Hill
      Avalon Style Entertainment
      Avantage
      Avant-Garde Creations
      Awem Studio

      Note: bolded names indicate companies that released a game within the last twelve months.