I'm going to guess that maybe the best part about making this game was doing 'research' (i.e., poring through as much fan works as you can looking at all the ships). This was a very interesting idea that was very simply implemented. As a Holofan, it's interesting to see the strength of each ship (as quantified by the score, relative to the game's database) and it also really tests your familiarity with the fanon relationships within Hololive. I also like the bonus you get by making pairs across branches, and especially the bonus I got for a 'Rarepair'.
This is a really interesting and fun test for the general Holofan.
As a point for improvement: I do realise it would mean having to gain permission from every creator used or referenced, but it would be a nice bonus to see a random fanw ork whenever you make pairs, be it a fanart pic, a screenshot + title of a game, or the title + website/link for fanfic. You don't have to put it in the gameplay itself; it could also just appear in the end score screen. You can do a recap of the higher scoring pairs the player got, mention the rare pairs, and then hyperlink the fan works or have them appear when the player hovers over the pair. Just as like a bonus for getting those more interesting pairs right. Again, it would mean securing permissions from the original creators of the fan works to allow you to reference their work, but I'm sure most (if not all) would be happy to have you direct people to their works.
Edit: it might also be nice to show the player how they're being scored. Like, are they being scored based on a ratio between all fan works involving the characters to fan works of just the pair? Or are there other quantifiers that are being considered? Also, what is the extent of the database? Did you go through all the fics in AO3? Or are you just counting the numbers next to the names in paheal.net? Displaying examples of the fan work would also help the player see and know that their guess is valid and that there is a database being referenced after all.
Good job overall! Congrats on the submission :D