I was going to say the original Doom on either the SNES or the GBA because that port is amazing given the hardware that it's running on... but you say they have to be outdated now, and I can happily go back and pick up either of those versions of the original Doom and blast my way through the whole campaign without a bother to them being "outdated" they still look and sound great.
Zero Tolerance on the megadrive was a tech marvel... but if you look at it in 2018 you'll see how they managed to pull off a FPS on the megadrives hardware, the majority of the screen is a giant window around a tiny play area, heck the characters ID card is pretty much the size of the play area.
Spinderella in Dynamite headdy was pretty awesome back on the megadrive as well... loads of that games sprites were gigantic and Spinderellas use of rotation and scaling was (for the time) very impressive to me.
Fancy hearing me on an amateur podcast with friends gushing over one of my favourite games? https://youtu.be/1I7JfMMxhf8