Touhou BGM on VGS app for iPhone and iPad

This application is a derivative work of Toho Project that plays Toho Project BGM arranged by me for the VGS Software Synthesizer, and is published in accordance with Toho Projects derivative work guidelines

Guidelines for Secondary Creation of Touhou Project:
https://touhou-project.news/guideline/

I have faithfully copied the music so as not to spoil the image of the original, but in order to make it sound good on VGS (or due to my lack of ability), I have arranged it slightly.

Below is an explanation of how to use this application.

HOME screen
- On the HOME screen, you can play songs by title and lock/unlock songs.
- Tap an unlocked song to play it.
- Tap the currently playing song, swipe to another title, or move to another screen to stop playback.
- Tap and hold on an unlocked song to lock the song.
- Tap the locked song or tap the unlock all button (at the top of the screen) to play the reward ad and unlock all songs.

ALL Screen
- In the ALL screen, you can play all unlocked songs in order.
- The songs are sorted in ascending order by title and track.
- If all songs are locked, nothing can be done on this screen.
- The "Favorites" tab allows shuffle playback of songs you have added to your favorites.

SHUFFLE Screen
- The shuffle screen allows you to shuffle and play all the unlocked songs.
- The shuffled playlist is generated when the SHUFFLE screen is accessed.
- If all songs are locked, nothing can be done on this screen.
- When displaying the shuffled playlist, a pop-up ad will appear at a certain frequency (about once every 3 hours).
- When you are in the shuffle screen, you can shuffle again by tapping SHUFFLE on the footer.

RETRO screen
- This is a reproduction of the UI of the old Eastern VGS (version 2 or earlier).
- Only unlocked songs are listed on the RETRO screen.
- Background playback on the RETRO screen is restricted due to technical reasons.

SETTINGS screen
- The latest songs can be downloaded from the server.
- The master volume can be adjusted.
- The KoBuSi mode can be changed.
- Support links are listed.
- The link to the original music (Apple Music) of Shanghai Alice Phantom is posted.

Others
- When the ∞ toggle is turned on, the currently playing song will continue to play indefinitely.
- The seek bar can be used to seek to any position in the song.
- If you return to the OS home screen or put the OS to sleep while playing a song in the Modern UI, the song will play in the background.

Offline use
- Almost all functions can be used in Airplane mode, except for downloading and unlocking songs, which can be done offline.
- However, only the downloading and unlocking of songs (playback of reward ads) require that communication is enabled.
- Please make sure that you have downloaded and unlocked all the songs on your VGS before boarding the plane.

In-App Purchase
- You can purchase add-ons to remove advertisements through in-app purchases.
- There are two types of ad removal items:
1. removal of reward ads (ads when songs are unlocked)
2. removal of display ads (full screen ads when always displayed & shuffled)

Support
- Touhou BGM on VGS is OSS under GPLv3 license.
- The developer website listed in the store is a link to GitHub, where the source code is available, so if you have any bug reports or enhancement requests, we would appreciate it if you could report them in Issues.