The stealth concept is very fun and takes a good opportunity to fill in an unexplored story piece! I like that it even directly references Silent Sinner in Blue with the title acronym.
I did notice that I had the fan before actually picking it up, which seemed to trivialize much of the stealth. If not for that issue, this could make for a very good stealth challenge proper.
The music sounds nice as well, and the entire game feels like a fun short Metal Gear Touhou. Well done!