In the same way words like “antique” and “vintage” bring about specific time periods and aesthetics, “retro” does as well.
In my opinion, “retro” gaming is a misnomer and “vintage” is more fitting for what people usually mean. Retro is something modern or recent made in an older style. Actual old stuff is “vintage”. So a game like UFO 50 is actual retro gaming; of course the definition gets more fuzzy when you look at ROM hacks that don’t even work on the original hardware of the base ROM. But if you buy an original old console and play the games from back then, that’s not really retro by the original definition.
However, I’m well aware that this ship has sailed