You are right! This is very good idea, we have started some talks with potential soundtrack artist and for repeatable I have just created a post on our patreon page refering to what you wrote here :) thank you for noticing that.
Unfortunately, this is all just Chapter 3 preview, we are still working on further events, but we couldn't just deliver chapter 3 completed. It was just too much for us for now. On our patreon page we will be releasing new versions which will contain next events.
Generally main story line ends with Rubina being abducted, which concludes 2nd chapter. There are some additional scenes in side events with Annie and Lisa.
This is last part, we are working on new events with new updates, watch for release notes on our patreon page. Also you can do some side events with other characters if you haven't yet
We need to gather more content to release new update. As we currently working on Chapter 3 which will take place in Hell (mostly), we wish to at least push some story in that direction first.
If you're interested on Patreon you can get newest version of the release (0.73.3), which contains a lot of improvements already, by pledging 5$.
Unfortunately at this point it's hard to make estimations when new public version will be released.
As I'm checking right now this is last event for this version, but we are planning to give her much more stories, actually it will be getting more interesting once she will encounter certain character.
We have stories written upfront but not yet implemented. There are many other chatacters we want to provide more stories and we were trying to release new public version
It is related to the main story which is still in production, becauise she is kinda related with chapter 3. We were trying to release chapter 2 as soon as possible, therefore she appears only for a certain moment in current version, but I don't want to spoil it. If we provide more stories to her, we will release probably an update to the public version introducing her more.
Sophia is a teacher in the school. There are some interactions with her available from second chapter. Many activities and meetings with girls open in second chapter, so be sure to get Anastasia first.
As for Tina, she is a side character, which means she will have some interactions/ scenes outside of the main story. We will be implementing dialogues with her (and other girls) in upcoming moths.
If you are curious about the progress you can check Patreon. Patrons get access to monthly/2weeks access to upcoming content.
You can get busy with Vicky, but you need to complete 1st chapter first, which is concluded by interactions with Anastasia. After you get Anastasia as waifu new options will be available.
