Woah this is quite an impressive entry for a Holojam game! Getting such a fluid movement model done in just 2 weeks is quite something!
One thing I would like to say is that the combat and mechanics were to the extent that I ended up sinking quite a few tries into this entry to get better. I still never beat the final boss though... despite many many attempts. But I was able to see tangible improvements throughout my playthroughs. Like actual tangible. satisfying, skill level increases, which for a game jam game is quite something.
I'm not the biggest Ace Combat player (I just played AC4 on PS2 back in the day) so I am not the best to judge this. But I talked a bit with a friend of mine who was an Ace combat player and got his opinions.
1. First of all, I enjoy the fact that you've taken the story premise seriously. I think that honestly, IMO Ace combat games and Ace combat-likes are ultimately very story driven. You play because you want to find out what happened, and the short little premise at the start helps express that quite a bit.
One change that I would recommend is to sprinkle more story snippets throughout the game. At the end, before you fight Shiori, you have quite a long (and honestly very interesting) sequence of dialogue. However, my friend thought the game was just an endless survival game before that point. The story actually is an incredible motivator and I think that having it sprinkled throughout can help players stay engaged and see what can come up next.
2. I think the difficulty is a tad too hard for what the game is trying to achieve. This sort of is a good rule of thumb for game jam games, but because there are so many games to play, having things on a bit of the easier scale is good for players. (For instance, I've neglected a lot of other games since I spent so much time playing this one). But also, I think that having things too difficult can actually hurt the story telling aspect, since players may end up feeling frustrated when the intended emotion was something else.
- This could potentially also be solved with checkpoints. For instance, if the lore reason that Shiori was so difficult (for me at least) is that you want to convey Shiori's skill/power, putting a checkpoint before Shiori can help still convey that point while also being less frustrating. At the moment, the difficulty can add some frustration which can interfere with the overall presentaiton parts of the game.
3. Controlling the plane with the mouse was a bit awkward. Controller support is difficult, and I understand if you did not have time to support it. However, having an option for keyboard controls can help a lot, as it would allow me to continuously turn in a certain direction without needing to reset the mouse.
Anyways, I really liked the game. One of the standouts IMO, and I want to learn more about this cool setting, where Hololive members are controlling high tech military equipment.
I think that games in more niche genres like this tend to suffer a bit in game jam ratings, as niche games don't hit with everyone. But regardless of how the game does in terms of ending rating, I think you've made something very cool and with a lot of promise for the time you have.