Thanks so much for your feedback! Totally agree that the public domain is mostly untapped (that's why we made our first game Prose & Codes!) Love the idea of different music for each theme, that would be so lovely. You've echoed some criticisms of other playtesters, so we'll be refining the Select a Theme state.
As far as being taken to the next puzzle rather than Select a Theme, that will be the way the full game works, but since there is just one poem per theme in the demo, it takes you to Select a Theme. Maybe we should include a few poems in a handful of themes rather than one per theme to better illustrate the way the full game will work.