All I remember is that around 2017/18 I was looking for something to play on my low end PC and somehow stumbled upon one of the fighting games (Think it was HM) but later on I learned it's a bullethell shooter and having never played one of those I tried UFO first (of all the games I could've picked!)
I liked the UFO mechanic back then despite how annoying it is (it allowed me to grind up a lot of life pieces just to lose them all to Shou, very fun!), but haven't picked up another one of the games until somewhat later at the start of 2020 with EOSD. I wanted to go through the mainline games in release order
Guess I always kinda knew about it since the bad apple!! arrangement but I know between me playing HM and EOSD I listened to a lot of the songs. So I kinda only really got into it because of the songs else I'd have just dropped the game years ago