Hi ! I'm the creator of BulletUpHell BLAST. With 200+ stars on Github, hundreds of users, BulletUpHell is the world's most feature-packed BulletHell Engine. I developed it over 2 years and it finally got out of beta a few days ago. People already used it for jams before, including this one, so you can be sure it's reliable. It's a plugin for Godot and my totally unbiased opinion affirm it makes Godot the best game engine to make bullethells.
With it, you can recreate ALL the attack patterns from your favorite bullethell games. It takes care of everything related to bullet spawning : patterns, bullet properties, event triggering,... Features include complex bullet movement (from math equations to custom drawn paths), advanced homing features, built-in animation and sound manager, ability to randomise everything, laser beams, and much more !
Here's the trailer :
You can download it here: https://bottled-up-studio.itch.io/godot-bullethell-plugin
Make great games ! Cheers