Thanks for the info Mizu. I actually already found out about some of these, like
Haika Brand and
Retrospective Koedo, and will add them to the OP alongside easy download with each track being separated.
Also added in “Silent Clangorous Discordance” by Popcat (A+), both PC-98 albums by Otobake, “Beyond The Starry Sky” by Dr. Fishenberg (B) and “Whispers of a Parallel World” by Orangeblugt (A-).
I think I've unfortunately run out of space on the first three posts now.
From other discoveries:
Prism’s album Prismatic is available either for purchase
https://prhythm.booth.pm/items/4774525, or for cheeky
download from here. It’s a solid album, but most of it is either a compilation of songs Prism used elsewhere (like BoSM Extra Stage) or 5 different arrangements of Desire Drive
Yoiyami’s Forbidden Score is available either for purchase
https://booth.pm/en/items/1930164,
cheeky listen here or for
cheeky download here.
Adding one I’ve missed. Eban’s micro-album called “The Grimoire of Luna Child” can be downloaded here
https://booth.pm/en/items/3629113 . It’s supposed to mimic The Grimoire of Marisa with one original uplifting song and second being an arrangement from Seihou Project.
Impious Scientific Beliefs… you can tell it is made by a newcomer. That being said, I hope they improve.
Cosmic Relics throughout Time and Space songs separated are available here now.
Same with Collision with Pagoda Tree(side-note, why does it look like something straight from BL visual novel? o_o).
Same with the The Tedious Tale of the Fabulous Beasts songs, I honestly don’t want to show stuff that can be considered a fetish/furry material here, but it being a crossover with another series (so not just being Touhou, but with YouShouYan) and having high quality, makes me fine with said decision... speaking of...
Mini-album “Embryons desséchés” by Alice Magic can be downloaded from this cheeky link
https://doujinstyle.com/?p=page&type=1&id=25942 . That being said, only one song there I think qualifies as Touhou-style. Another album has been already produced by their artists in the meanwhile
Called “Arithmetical Doll”
https://booth.pm/ja/items/6191051 3 albums by mag/アトリ can be bought here:
https://mysterycircle.booth.pm/ or
got from this cheeky place \. Mostly basic MIDI instruments, but it’s still solid stuff.
I’ve finally put all the albums by モン魔理 / Mon Mari in order and I grew to like their style. They’re all available from their Booth.
https://monmaris.booth.pm/
SHO’s mini-album “Nostalgic Adventure” consisting of one new song and 2 arrangements from Aogami series can be listened to here
https://www.youtube.com/watch?v=3T4BjouETKQ or downloaded here
https://drive.google.com/drive/folders/1-3xz_4SiE4uBLxJEi6hM6gZJ3l8WoYkD?usp=sharing as separate tracks. I do highly recommend giving a listen to the first track at least, it being the titular track.
Yorin has released a 4.5th album called “Princess of the Full Moon.” which is available from here for free
https://yorindoshin.booth.pm/items/6097003 . It’s technically only arrangements of official songs, but in unique ways like Lunatic Princess melodies using progression and instrumentation of Little Princess. Adding it here for the sake of consistency since I’ve included all other Yorin’s albums I could get my hands on.
Fans of PC-98 and ZUN’s Strange Works, rejoice, there’s an OST by TrojanHorse711 for the supposed upcoming fangame “Remembrance of Past Prayers” with each character having two themes/reusing for the second run of the game and it’s pretty good if you like old Famitracker style.
https://www.youtube.com/playlist?list=PLVmu8Q4khagAwHFW39mpnwOLq-hfczN2E Updated Sunshiny of Frenzy and Paradoxical Esoterica with missing/beta songs. Fixed Obsolete Lesedrama link, it was previously linked to the wrong album.
EDIT: Also I've risen Boundary of Sacred Mountain all the way to from B- to A- (it was on top of third post, now it's on top of second post) because I've realized how good it is. Also fixed description for both of Otobake's new additions (I wrongly assumed the Fantastic Modulation is just IN in PC98 without anything more and that Touhou Chip-Tune is a chiptune album without any original compositions, it does have them and it's still PC-98 style). Slowly adding back comments and notes.
Lastly, there’s this dude uploading Megaman-like 8-bit style arrangements of Touhou songs
https://space.bilibili.com/305632166/video , including fan games and fanalbums I’ve already covered. Thfanmusic also does that, but is far more known I feel. If you haven’t check out their work, but you don’t want to make an account for bilibili,
I’ve compiled my favourite arrangements here.
