Thank you very much for twee2!!
After installing ruby2 (on xubuntu only ruby1.9 seems to be packaged) by hand
twee2 worked out of the box as described by your fine documentation.
I’m very happy now to explore the Twine2 world offline with my favorite text editor.

Seems to be based on a straight concept, works out of the box, is easy to use, and the result file goes fine into Twine2(online) via import – very nice.