I know that remakes and remasters are contentious, but let’s pretend whatever game in question you’re thinking of is handled with the utmost care by your favourite devs and they absolutely nail it.
Mine would be Shadow of Memories (called Shadow of Destiny in North America). It’s legitimately one of my favourite games of all time but it kinda flew under the radar and I haven’t met many people who know of it let alone played it. Seeing it get modern graphics, maybe some expanded mechanics, would be soooo cool.
Its not that old (although that does fit the theme) but Hotline Miami 1, and to a lesser extent, 2. Both are limited a lot by the engine, and by the small scale of their development. If they could be re-made in a new engine, with some modern customizability and QoL features, as well as added polish on things like the door physics, I think it could go a long way to ensuring they stand the test of time.