Line Art (2016).
The residents of Flatland can, in theory, see only the linear surfaces of the flat things in their world.* Those linear scenes however are typically colored with the various shades of the spectrum (the visible spectrum of light is a bit wider, in nanometers than in 2D) and most Flatlanders are tetrachromats, so their visual world is not so impoverished as we might imagine. So except for inconveniences like not being able to tie knots or have axles attached to their wheels, life is not so flat after all. Their brains work relatively quickly, though coolent is a bit harder to distribute when you can't wrap capillaries around axons, and of course weaving (a mainstay of 3D clothing) is out. But their social lives are every bit as entertaining and frustrating as we have come to expect of our own. I'm sure I'll have more to say, but you should realize that in 2D hiccups are a fatal disease, since there are no tubes in Flatland. Bodies are held together by the gripping of the left and right sides of the intestinal track.**
- Like we see the 2D surfaces of the 3D things in ordinary Euclidean 3-space, using parallax and depth cues to deduce distance and depth.
**There are other options, but some of them are unpleasant to think about.