I've never played Earthbound, but this thing is nightmare fuel.

The soundtrack alone is beyond unsettling. Idk what it is about older games with more midi/lowfi music, but it's so much creepier than anything modern. I guess it just sounds more alien and distorted compared to recognizable instruments.

Plus the very concept of the guy, no physical form, and during the final phase he's the entire background with no foreground sprite like all other enemies, and it forms the outline of fetuses to symbolize how he's regressed mentally in his insanity.