Um, yeah, Duck Hunt is kind of the definition of retro.
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What is the definition of retro?
Dictionary.com:
ret·ro /?r?tro?/ Pronunciation Key - Show Spelled Pronunciation[re-troh]
–adjective Informal.
1. retroactive: retro pay.
2. of or designating the style of an earlier time: retro clothes.
Technically, a game that came out yesterday can be considered "retro," then. Hm.