>>712782029
There's very few concrete elements I can point out. I love bittersweet and tsukihime has that in spades. I was caught off-guard and impressed by how well defined of a character shiki is in spite of being a self insert, and on top of that I just naturally agree with his positive nihilistic outlook. And lastly the story's themes (life is fragile so appreciate what you have, don't obsess over the past, don't fuck your sister or you're doomed for failure) really resonated with me.

However, a really big part of it that I can only explain with a wishy-washy answer, is that everything about it just clicked with me from the word 'go' when I saw the poster with arcueid on the wikipedia page.
The poster, the immediate opening before you even see the menu, the menu music, the prologue and Aoko, the game's font, meeting arcueid, literally everything just clicked and sucked me in. The character designs are simple, yet iconic. The soundtrack has a great 90s feel. Those two combine with the real life photo CGs to give everything an amazing sense of place and time; the whole thing is a time capsule that transported me back 20+ years. It's just right up my alley, I don't know what else to say