| Atari Europe | Publisher | |
| Atari Europe S.A.S.U. | Publisher | |
| Atari Games | DeveloperPublisher | |
| Atari Hunt Valley | Developer | |
| Atari Interactive | Publisher | |
| Atari NA | Publisher | |
| Atari SA | Publisher | |
| Atari, Inc. | DeveloperPublisher | |
| Atari, Inc.KO,NA,PAL | Publisher | |
| AtariAU | Publisher | |
| AtariAU,NA | Publisher | |
| AtariAge | Publisher | |
| AtariEU | Publisher | |
| AtariKafa | Developer | |
| AtariNA | Publisher | |
| AtariNA,PAL | Publisher | |
| AtariPAL | Publisher | |
| Atarisoft | DeveloperPublisher | |
| Ataro | Publisher | |
| Atelier Double | Developer | |
| Atelier Garbage | Developer | |
| Atelier Mimina | Developer | |
| Atelier Sentô | Developer | |
| Atelier-Sai | DeveloperPublisher | |
| Ateliér Duchů | Developer | |
| Atemly Games | Developer | |
| Atent Games | Publisher | |
| Atezai | Developer | |
| Athakaspen | Developer | |
| Athena | DeveloperPublisher | |
| Athena Co. | Publisher | |
| Athena Hollow | Developer | |
| Athena JP | Publisher | |
| AthenaJP | Publisher | |
| AthenaParadigm | Developer | |
| Athletic Design AB | Developer | |
| Aticora_Games | Developer | |
| Atium Addict | Developer | |
| Atiya Nova | Developer | |
| Atlach | Developer | |
| Atlantean Interactive | Publisher | |
| Atlantean Interactive Games | Publisher | |
| Atlantis Interactive Entertainment | Developer | |
| Atlantis Software | Publisher | |
| AtlasAndCo | Developer | |
| AtlasDev | Developer | |
| Atlingworth | Developer | |
| Atlus | DeveloperPublisher | |
| Atlus (NA) | Publisher | |
| Atlus Co. | DeveloperPublisher | |