Kinda hate to bump an ancient thread, but I was discussing something similar on discord about the the spookiness scariness of Waixing and Mars games, there's just something about their craft that has the creeps. Just about the majority of their games have pretty bad music that has stuck in my head and kept me up the last few nights, and I could go on forever about them, but I think I'd be better off just listing some select examples.
Super Contra 7 is definitely known for it's pretty bad music, but there's just something scary about all the boss music in that game, especially the weird carousal robot boss's music, all the boss music definitely has that old sci-fi horror movie vibe to it which is a vibrant contrast to Contra's usual rather upbeat rock tunes. Sci-fi horror soundtrack arranged through NES's soundchip is definitely haunting and unnerving, in fact I'd probably have to admit many of the boss designs and even some of the jagged animations give me the creeps.
Pokemon Gold for NES also generally has some pretty creepy tunes, the title track, while based off an old piano composition; just sounds haunting and cursed, even if it's not really intended to be creepy. Then of course there's the battle theme which feels more in place in a horror game than a pokemon game.
Then of course is Darkseed, the original game is spooky enough and gave me nightmares a good decade ago when I discovered it on youtube, but the NES bootleg definitely has it's share of scariness to it, there's the one song in the game that definitely gives a creepy and mysterious vibe, and then of course there's the creepiness of the graphics and their attempt to recapture the source material, looking creepy at the same time.
I could probably go on about more things in other Waixing/Mars/pre-Waixing games that give me the creeps like badly digitized sprites, uncannily creepy animations, etc, but I'd probably end up repeating myself quite a bit, and many might just sound lame.