Bullet Hell games like this one live and die on visibility. You have some good patterns here, and Ikaruga-style games are always gonna be fun, but it's very hard to gauge the size and hitbox of both the player character and the individual attacks. Some of the final boss attacks in particular are nigh-impossible to avoid, because of how close the element waves spawn. Also, some of the sound effects seem ripped from Undertale, which might be in conflict with the no-fangames rule. There's some good stuff here, but there's plenty of space to improve.