There’s probably a ridiculous amount of things to talk about on this topic, but I’m going to focus on the implications of trying to make a game with a 1D viewport, as if viewed on a 1D display.
It’s intuitive to consider analogues between 2D and 3D beings when comparing certain aspects of their lives. For a game, we could consider that we see a 3D world as a 2-dimensional image (disregarding the argument about whether having depth perception qualifies us as “seeing in 3D”), and so a 2D display suits our needs perfectly. Similarly, we can imagine a 2D being seeing their 2D world in 1D, and using 1D displays for imaging. Note here that, as 3D displays are possible in 3D space, 2D displays would probably be possible in 2D space. In both cases, the applications are limited.
We could use a 1D projection of a 2D world on a 2D display easily. It doesn’t necessarily have to be a line-- in fact, I don’t think it makes sense to do this. Just as our 2D vision doesn’t have perceivable borders (when there are no obstructions, including facial features, we don’t see an image surrounded by nothing as if floating in a void, we just either see things or don’t see them), I would imagine that 1D vision wouldn’t either. I suppose a good reproduction of this would be to use a “stack” of colored bars that represent a 1D image.
A Flatlander on a circular planet (making up my own scenario here) doesn’t have an analogue for left and right, since these are relative to a direction in x and z, where normal to the planet’s surface is along the y axis. They do have an East and West, though, since these are relative to the planet. They would be like clockwise and counterclockwise to a 3D observer, as long as Flatland couldn’t be viewed from the “back”. They would also have an up and down analogue, since that can be relative to any asymmetrical object or could just be in reference to the toward and away directions relative to the ground. It would be easy for them to tell which way up is in most situations because of gravity, the same as with us.
A locomotive critter with an eye living in 2D space would find it convenient to have a swiveling head so that it could look both East and West. To change the direction it’s looking, it would probably swing its head past up. If we imagine the 1D view of this creature as it does so, be it as a line of pixels or as a stack of bars, down would start at one end of the view before the change, but end up at the other end after. Physically, the eye turns over so that the side that faces up before the change faces down afterward, so this makes sense. However, the being wouldn’t perceive this as their view being “upside-down”, because both orientations are normal. It would be able to tell which orientation it’s in, though. Because of all of this, I think a left-to-right representation of a 1D view from a 2D creatures makes more sense than up-to-down in all cases-- up-to-down would confuse us, because we have specific meanings for these directions, but left and right are interchangeable in general. Edit: A friend of mine mentioned that a 2D creature could have an eye for each direction. I consider this to be the same as 3D beings with eyes that point different ways, where they have a wider viewing angle. A squirrel can see to the left and right at the same time without moving, and a 2D being could see East and West at the same time.
I’m going to stop here, because I think I’ve already made this too long. The point is, this is the logic I would use to arrive at my choice for how to display a view from a 2D world in a game. Anyway, here’s a screenshot from my upcoming 2D FPS:
Got it from a friend, who downloaded it from the internet, so I guess that fits the image that it isn’t exactly a blockbuster title.