Projects in the topic usability

I like to try out if it is possible to write a program that does not have any kind of the traditionally separated documentation (like external files that contain the documentation texts or comments in the program code). Instead all documentation must be implemented as code at the same place where the matching functiomnality is implemented (i.e. each function implements also its documentation). In the end the user should get only the executable that he can run to let it do the intended functionality and also to provide any kind of documentation. What I do not want is a dumb '--help' option that lets the program spit out its built-in documentation. What I would like to have is that the user can run the executable in some kind of self-inspecting way. I mean: While it does the intended functionality, it can also provide documentation so that the user can explore the program while running it. In the end the user experience should be more like a text adventure ;-)