gaming vs retrogaming

gaming and retrogaming both are nouns.

Word	Noun	Adjective	Verb	Adverb
gaming	Yes	No	No	No
retrogaming	Yes	No	No	No

As nouns, retrogaming is a hyponym of gaming; that is, retrogaming is a word with a more specific, narrower meaning than gaming:

gaming: the act of playing for stakes in the hope of winning (including the payment of a price for a chance to win a prize)
retrogaming: The hobby of playing or collecting older video games and computer games.

Other hyponyms of gaming include sporting life, bet, wager, gambling game, game of chance, throw.

gaming (noun)	retrogaming (noun)
the act of playing for stakes in the hope of winning (including the payment of a price for a chance to win a prize)	The hobby of playing or collecting older video games and computer games.