The original 360 didn’t even come with an hdmi port, I remember playing Armored Core 4 on a crt. For me anything that was meant to be played on a crt is definitely retro.

“Massively underpowered” switch hardware is much more powerful than the 360 as well, with games like Skyrim, RDR, Bayonetta, all running much better than they ever did on 360 or PS3. So if that’s retro…

Emulation has nothing to do with it, Saturn emulation is not great still and it’s an old system, original xbox as well. All the while PS3 emulation is pretty good now and PS3 is newer than the 360. Hell, Nintendo Switch even got an emulator in the middle of its life cycle, does that make it retro?

Speedball 2 Brutal Deluxe and Cannon Fodder are must try (there are both Amiga and dos versions for both).

Lemmings is really good. Original Worms. Lost Vikings. Syndicate.