Darius Cozmic Collection really opened my eyes to Darius Gaiden and how great it is, but I've heard a lot of people are a bit intimidated by the difficulty. I'm not personally great at shmups but I managed to 1cc it so I wanted to share my sloppy, initial 1cc with commentary to help people understand the game a bit more and give it a shot themselves!
Also apologies for my sniffling- I've got awful allergies.
bofner's speedrun: https://www.youtube.com/watch?v=JUZPZr8hWVE
MathUDX ACEHLQV score attack: https://www.youtube.com/watch?v=cv_CW_alNiA
shmups forum post: https://shmups.system11.org/viewtopic.php?t=79
Gamest Mook (great guide Japanese only): https://archive.org/details/dariusgaidengamestmookvol.6/mode/2up