Illusion Software is a Japanese software firm which concentrates on producing 3D eroge titles exclusively for the Japanese market. As a developer of eroge, they are notable in that, unlike most of their counterparts, they focus on three-dimensional models instead of 2D hand-drawn art, and favor iterating improved gameplay engines over narrative development and dialogue trees. Originally publishing and developing titles under the company name Dreams, they changed it a few years later to Illusion (possibly to avoid confusion with Taito developer Dreams, Inc.).
Originally producing narrative-driven titles, the 3D models featured in most of their titles have permitted the growth of a very large modding community for Illusion's games, making them something of an adult Japanese Bethesda among eroge developers. Embracing the community's tendencies, more releases such as the Artificial Girl series and Artificial Academy have capitalized on the variable nature of the real-time 3D engine and focused instead on create-a-character models, usually including interchangeable parts that allow for the creation of copyright-infringing characters, such as options for Chun-Li hair buns. Additionally, the company has eschewed most of the plot and game elements from their original releases such as stealth, fighting, or action to focus almost entirely on increasing the level of interaction during sex scenes.
Even though Illusion has never released a game outside of Japan, the western controversy over interactive rape sequences included in titles such as the Battle Raper series and RapeLay have resulted in the company blocking most internet users outside of Japan from accessing their website. They have issued public statements that their titles are specifically and exclusively meant for release only in Japan where such inclusion in games and fiction was permitted, however changes to legislation in Japan have made it unlikely that direct sequels to any of their rape-focused series will be developed.