A Motherlike is a game that has... something special that sets it apart. Sometimes they're funny, much of the time they're RPGs, maybe they have a singular voice, perhaps an interesting atmosphere...
What brings them all together is a uniqueness in each title, a commitment to vision, story and art, and a particular feeling at the end.
Like a Mother game...
(And of course, the games that fit in this category are subjective, not definitive, save a few! Make your own personal list, I'd love to see it!)