Please refer to the Technical FAQ.
While development of King's Quest II: Romancing the Stones was in progress, writer Daniel Stacy already had several ideas for a possible remake of King's Quest III. At the time of the King's Quest II remake's initial release (in December 2002), a remake of the third King's Quest game was the most popular choice for AGD Interactive's next project, according to a "Future Remakes" poll, which fans voted in. So both the wishes of the public and the team alike warranted the decision to start developing the game. The foundations of the King's Quest III Redux project were already laid out while King's Quest II: Romancing the Stones development was still in progress, but full development on the title didn't start until two months after the initial release of Romancing the Stones.
Yes and no. The King's Quest III Redux project was originally set up as an experiment to see if we could get a project going that could efficiently be developed alongside the Quest for Glory II remake. Full development on both projects commenced around the same time in early 2003. The development phases of both projects more or less ran side-by-side. As time carried on, the boundaries between the projects became blurred. The Quest for Glory II remake team lent a hand to King's Quest III Redux, and people who started out on the King's Quest III Redux team went out of their way to help further improve the quality of AGD Interactive's other projects.
The game is not quite a 1:1 remake on the same level that AGD Interactive's King's Quest I remake was. Nor is it a complete overhaul like King's Quest II: Romancing the Stones is. King's Quest III Redux lies somewhere in-between. The word Redux is typically used in the film world to indicate a different interpretation to a familiar story and we felt that the word described our vision for King's Quest III quite well, so the name stuck.
At the time AGD Interactive took Nuvynuke's King's Quest III project under its wing, we already had enough experience in game development to understand that the initial enthusiasm that accompanies a new project is never enough to see it all the way through to completion. It requires devotion, talented contributors, good management and always more time than you plan out beforehand. Since we did not know how far the project would get at its inception (and we did not want to get people's hopes up only to let them down later), we decided to move the King's Quest III Redux project underground from the very beginning. This would save our fans from disappointment in the case of development setbacks (of which we experienced several) and it would also spare the team from feeling pressured by demands for constant updates from the public.
Then go right ahead! The King's Quest III Redux remake was released on February 24th, 2011.