Oh, it's Touhou in a Zelda dungeon! Interesting! I literally thought this is going to end after the first boss, being an LD jam game and all.
Little did I know...
I initially disliked the idea of having a time mechanic that makes you rush through a dungeon you'd want to explore meticulously. Not to mention that after all lights had went out, that 'gotta go fast' aspect disappears completely.
But as floors went on, the mechanic started to make sense: the rooms were very repetitive, so you actually WANTED to rush the game instead of conscientiously killing every enemy in every room.
And oh boy did that mindset make the later floors much more enjoyable. I actually made into fourth floor's boss while the lights were still on there and almost had it - but it got me just before the end!
I liked especially the third and fourth boss - there was a winning strategy to be found, and wrong moves could be fatal.