I've noticed with "retro"-looking games like Stardew Valley, people will say they look like 80s games. No, they look like 90s games (at worst). People forget how primitive the graphics were at 320x200x16. They were great at the time, and people did some ingenious stuff to get the most out of those systems, but they couldn't display anything like what's called retro today.

Ye it is a strange genre. Stardew Valley seems to have way better graphics than say Jack Jazz Rabbit and Red Alert.

Also many retro looking games adds pixel effects that weren't there on crt:s. Games of that era were quite smooth looking.