Founded in 2001 by Britney K. Brimhall and Christopher T. Warren, under the name Tierra Entertainment, the team started working on a remake of the first King's Quest game, intending to bring it up the standards of King's Quest V and VI, both graphically and gameplaywise. After securing themselves permission from Universal Interactive, who held the license to Sierra's adventure game series at the time, they released their remake of King's Quest I Quest for The Crown in 2001, which was a 1-1 remake of Sierra's own remake for the SCI engine from 1990, but updated to run in VGA colors and use a point-and-click interface instead of a phaser, with later updates adding speech and optimized music.
In 2002, the team released their remake of King's Quest II Romancing the Throne. The remake was, unlike the previous one, a total retelling and overhaul of the original game, and changed the subtitle to Romancing The Stones. The game featured several new and changed puzzles, fleshed-out characters, and an expanded storyline with some Arc Welding to future games in the series.
In 2003 the group charged their name to AGD Interactive, AGD meaning Anonymous Game Developers. In their pipeline, at the time, was a remake of Quest for Glory II, which was delayed multiple times, missing both a 2004 and a 2005 release, before finally being released in 2008.
February 2011 saw the release of the team's remake of King's Quest III to Heir Is Human, which got the subtitle Redux, and it is something in-between of their other remakes, featuring a couple of expanded puzzles and characters and some references both to other King's Quest games and the subplot introduced in Romancing The Stones, although not to the same extend as that installment. AGD also announced would be the final release under the AGD Interactive label. The decision was, according to various members of the team, based both on a desire to focus on the development of original and commercial projects, released under their alternate label, Himalaya Studios, and because securing further permission to create Sierra remakes from Activision, the current holder of the rights, proved hard.
Their site can be found here.