spillikins vs child's game

spillikins and child's game both are nouns.

Word	Noun	Adjective	Verb	Adverb
spillikins	Yes	No	No	No
child's game	Yes	No	No	No

As nouns, child's game is a hypernym of spillikins; that is, child's game is a word with a broader meaning than spillikins:

spillikins: a game in which players try to pick each jackstraw (or spillikin) off of a pile without moving any of the others
child's game: a game enjoyed by children

spillikins (noun)	child's game (noun)
a game in which players try to pick each jackstraw (or spillikin) off of a pile without moving any of the others	a game enjoyed by children