There will be a concrete ending to the game but as the episodes progress there will be more and more interactivity/sandbox stuff yeah. Glad you like the idea!
Nice. If you plan on making another game set in this universe can I recommend this style of gameplay for that one? keep In mind that this is just a suggestion because I believe that games are at their best when devs create what they want to create but that doesn't change the fact that constructive criticism, recommendations, and general feedback are all valuable in regards to the creative process. And in all honesty when it comes VNs I think being able to interact with the characters in and outside of the story is almost always a plus. Not to mention it's always nice to have more content. This way the content creator can experiment more with new ideas and more forms of fun and creative content and the player has more options in regards to how they can enjoy the current content as they wait for new content to be released. Again, to clarify, I'm not trying to tell you how you should or shouldn't make your games. I'm just throwing an idea/recommendation out there.