The news sections contains a pretty good chronological description of what was developed first.
Basically it started off as a landscape renderer and then migrated to a game when I thought that would be more fun. I had already had a lot of OpenGL experience with other smaller games I have written. This game however is far more modular partly due to the experience with the other games.
I don’t really have any great testing stratagy (at present) I just play then game and test any new features as they are added. I also rely on posts here and e-mails.
Writing test plans and specs it far too much like real work