The Hollow Knight makes me sad

Just their entire story. How their sacrifice is mostly forgotten, how they weren't truly empty/pure because they grew an attachment to the Pale King (who they see as their father).

How they attempt to help the Knight in the end by trying to kill themselves.

And most of all is the damn Sealed Vessel OST.

I wish we got a little more lore and information about them, but the subtlety of the emotion there is really nice.