I haven't actually read this specific fanfiction about miyu and kanata kissing. But generally, such a fanfiction might explore the relationship between the two characters in a romantic way. It could show their deepening feelings through this kiss, perhaps as a turning point in their relationship.
There's not enough information to determine its widespread popularity. However, if it has received positive reviews from players and critics in the visual novel genre, it could be gaining popularity. Some factors that can contribute to its popularity are interesting characters, a well - written plot, and appealing art style. If it lacks in these areas, it may not be very popular.
Sorry, I don't know the precise cancellation date. Maybe it was cancelled because of financial reasons or a shift in the target audience. Try doing a search on popular entertainment websites for the accurate information.
I'm not entirely sure as I haven't played it in detail. But generally, visual novels often involve a story with characters, a plot that unfolds over time, and usually some sort of choice - making elements for the player. It might be about relationships, an adventure in a particular setting, or some sort of mystery within the 'ao no kanata' world.
Often, miyu is written as someone who is very in tune with her emotions. This can lead to some really interesting character interactions in fanfics, especially when paired with kanata. Kanata may be seen as a bit more of a mystery, and fanfic authors might explore his backstory and what makes him tick in relation to miyu. For example, in some fanfics, his past experiences could be what shapes his relationship with miyu, whether it's through shared traumas or simply different outlooks on life that they gradually come to understand about each other.