The original game came out in 1999, and it is showing its age in many ways. It no longer even runs on the newest version of the Macintosh operating system, and it's starting to get very shaky on Windows 7, especially the 64-bit version. We don't want this game to disappear from the face of the earth, so a major retooling is necessary.
In addition, we want to release Avernum on the iPad, and that too requires major modifications from the ground up.
So we have two choices. Let it disappear or redo it. We love the game too much to pick the first option.