1. Companies starting with I:

      ICOM
      Id Software
      Idee Software
      iEntertainment Network
      Ignition Entertainment
      IJG
      Illustrated Memory Banks
      ImageBuilder Software Engineering
      IMagic
      Imagine Software
      Imaginengine
      ImmersionFX
      ImpactGames
      Impressions Games
      Impulse
      IMS Productions
      Independant
      Inertia Game Studios
      Inevitable
      Infinite Interactive
      Infinity Ward
      Infocom
      Infogrames
      Inline Design
      Innovative Design Software
      Ino-co
      Insomniac
      Instant Software
      IntelliCreations
      Intelligent Statements
      Intelligent Systems
      Intelligym
      Intellitech Systems
      InterAction Studios
      Interactive Classics
      Interactive Magic
      Interconnect Inc.
      Interex
      International Publishing & Software
      Internet.com
      Interplay
      Interstel
      Intracolor
      Introversion
      Invasion Interactive
      InXile Entertainment
      Ion Storm
      I-play
      Iron Lore Entertainment
      Irrational Games
      Island Software
      Isopod Labs
      iSquared Games
      IT Territory Nord
      iTunes
      Ivolgamus
      iWin

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