Coincidentally, I recently finished playing
The Fallen Spirits. Truly a good candidate for a featured episode
But first of all, the bugs (playing on 2b3):
- You can pass the magical door in Night Oasis with only four Spirit Coins collected
Stario briefly appears after you defeat the second boss
- During the first sequence of the final fight, the scenery briefly distorts about every 30 seconds. Only slightly irritating though.
- Not really a bug, but in the download there is a savefile contained in which the game has been solved to 95%
I like the idea that there should be secrets in every single level

Also, I appreciate your efforts in thinking of ever new hiding places. Like I said, normally I strongly dislike illusion walls and puzzles depending on invisible blocks, but you've placed them so skilfully that I enjoyed the treasure hunting nevertheless. Even though I found almost every Spirit Cell on my first attempt.
Sometimes I wished there would be more than just one or two kinds of enemies per level, even if they be vanilla ones, but I do suspect this would change the overall feel of the game significantly. In any case, it was great to see so many custom sprites
Also, I'd greatly appreciate if
something changed after you collect the 100th Spirit Cell. Most importantly, the Spirits should stop talking like the Spirit Kingdom was still in distress. A soundcheck room would be nice, too. However, to be honest, I wouldn't know what to do about
Stario. Leave him be and ignore the inconsistencies? Or replace him with good Spirits? Then the finale would be unrepeatable. Unless there was a bonus room from which to access all boss fights again... Maybe, with 100 Spirit Cells regained, the Spirits (re-)gained the ability to open portals into the past, but only the near past and to very specific locations.
Finally, I find the BGM really fitting

I mean, you even have a calm version and a lively version of the same melody, for the hub and for the levels, respectively. Not only that, but
you composed all 20 BGMs yourself!

That's amazing! In particular, the Spirit Haven theme is one of the best musics I've ever heard! I still have an earworm from it (which made finding my way through winter sale a lot more pleasant. And how appropriately so:
EXAM - Determination, EXAM - Endurance etc. - might as well apply to shopping tours imo

).
Hopefully we'll hear more from you in the future!