Thank you so much! I'll reply here while also taking into account your reply to my CellShocked comment.
First of all - for all of my games so far I used SHMUP Creator engine, which is a fairly new no-code engine designed for shmups and bullet hells specifically. Everything related to performance is handled by it, and it's really really optimized - uncapped framerates and up to 8000 bullets on screen at a time with little to no slowdown, depending on pc. For bullets specifically I believe it uses meshes: https://www.ogre3d.org/2022/09/10/game-highlight-shmup-creator (the engine is written in Ogre3D so not sure how useful the article will be, but perhaps some concepts apply to UE too)
Not having to deal with performance and behind the scenes coding stuff is probably the main reason I prefer no-code engines like SC or RPG Maker, props to you for using a big gun like Unreal! ...which I heard is pretty hard to use for 2d, and off the top of my hat I can't remember any shmups or bullet hells made with it. I'm sure it's not impossible though ^^'
As for Rotschwert, I'm really happy you noticed the music timing bit - when I first started doing that it quickly turned into an addiction and now I have to actively stop myself from spending hours to time it perfectly lol. And I'm happy you enjoy the patterns - they're not as elaborate as in Rotschwert's parent game, Nullschwert, since I wanted to focus more on combat and quick repositioning rather than tight dodging, but I'm glad to hear they were still sufficient ^^
And yes, I'll definitely finish the game after the jam, the scope and structure of the game were already set in stone during development, just didn't have enough time to implement the rest of the levels. I'm not sure when it will be released since I still need to work on the main project, but unless a cellular alien infestation wipes out humanity - it will be completed. Thank you again for the kind words and feedback!