I was also gonna say "Returnal", maybe specifically the second boss. It took like 2 years or more of off-and-on playing to beat the game... it was oh so satisfying, but damn that game can be brutal

I looked up some tips and tricks that helped, but it really came down to "just be better"... I've gotten way better at this point, but the learning curve was steep and long

I'm playing Saros now (Returnal's 'spiritual sequel'), and it's wayyy easier in comparison. Not in a bad way, cause it's really fun... but after playing Returnal, I was already prepped for some bullet-hell dodging

Would highly recommend Saros, cause you'll definitely be able to beat it and it may entice you to keep striving for that sweet, sweet Returnal end game