Funny enough, Kizuna Encounter.
HEAR ME OUT.
It starts kinda chill, CPU isn't so bad early on, but the atmosphere is really off. The streets are wrecked, deserted. There's crows everywhere. You NEVER see a person on these backgrounds. It's really off-putting once you realize it.
And then King Leo shows up, and the game turns upside down. That guy is one of the cheapest bosses in SNK history. Reads everything you do and punishes accordingly, dealing tons of damage in the meantime. Last time I beat him it took me AN HOUR.
And you'd rightfully think that's it.
No.
Suddenly, a sword goes through the mf's heart, and a goddamn crow is perched on top of the sword.
I remember seeing this as I was younger and almost shitting out bricks.
The order select screen is your characters against the freaking crow on the sword.
He then morphs into Jazu, crouches, starts doing some black magic and the whole background turns into some twisted version of the palace you were in earlier, not to mention his theme song. Nightmare fuel.
Granted, he's a little easier than King Leo, and it definitely took me less tries, and the ending despie being bittersweet as hell, with the ending song and King Leo SOMEHOW staying alive, I'll always have a funny memory of facing this boss sequence for the first time. Scared me more than any horror game ever could.