The game Castle, the first game developed by Beem Software. See the folder "Old Versions" for the original QBasic source code. The current version has been through quite a bit, but now I pretty much consider this software complete and will most likely never do anything with it again.

It's actually kind of cool in that it has it's own scripting language called CastleSCRIPT so technically you can create any kind of text adventure that you want using this application.