I found it because another fandom I was in used its characters to do an animation of Kero ⑨ Destiny, and so of course the original Kero ⑨ Destiny animation was recommended. I found a lot of other Touhou animations through that, got curious what all these characters were from, and found it. Took me awhile to actually play the games instead of just being in the fandom and knowing the fandom personalities and the like.