0 Dimensional - a point (a dot)
1 Dimensional - part of a line; a line segment (a stick)
2 Dimensional - part of a plane; often polygons (especially in video games).  Two dimensional shapes have a one dimensional border like a line segment or a curve.  This defines the two dimensional interior.
3 Dimensional - part of space, often polyhedrons (especially in video games).  Three dimensional shapes have two dimensional borders such polygons.  These borders define the three dimensional interior.  When you see calculations about number of polygons rendered they are talking about the exterior of a shape.  More polygons enables more smoothness and definition.

The paddles are 1 dimensional and technically the ball is 0 dimensional.  (A point is zero dimensional.)  Two dimensional objects have an interior.  Their borders are one dimensional.  That is what makes something a two dimensional object.  It has to have an interior.  Also, the controller on Pong is one dimensional.  You can only move up or down. 

That is why I'm saying Pong is a 1D game.  It has nothing to do with what happens on screen.  We call Mario 64 a 3D game, but it is still on a 2D screen.    I'm saying Pong is 1D, because the graphics and controls are 1D.  The graphics of Mario 64 are 3D, and it uses an analogue stick.  That is why we call it 3D.  Pong uses 1D graphics and 1D controls.  

One dimension is like the x-axis.  You could move left-right only or maybe up-down only.  Moving in all 4 directions is 2D.

Actually, I misspoke.  A dot has no dimension.  It is 0D.  In any math class, your teacher has to make the dot big enough for you to see, so it technically has a height and width.  But your math teacher is still going to tell you it has no dimension, because they are talking about the concept of a shape and not the literal height and width.

No, I am being perfectly honest.  The biggest mistake I've made is that I misjudged how much (or little) people understand geometry.

A square has an interior, and so does a rectangle.  That is why the objects in Pong are not 2D.  The controls are clearly not 2D either.  Gaming started out as purely 1D in the sense that the graphics and controls were purely in 1D.

Here is a quick geometry lesson.  Go ask any mathematician and you may be shocked that they tell you the exact same thing.

0 Dimensional - a point (a dot)
1 Dimensional - part of a line; a line segment (a stick)
2 Dimensional - part of a plane; often polygons (especially in video games).  Two dimensional shapes have a one dimensional border like a line segment or a curve.  This defines the two dimensional interior.
3 Dimensional - part of space, often polyhedrons (especially in video games).  Three dimensional shapes have two dimensional borders such polygons.  These borders define the three dimensional interior.  When you see calculations about number of polygons rendered they are talking about the exterior of a shape.  More polygons enables more smoothness and definition.

So if you look at Pong, Generation 1, it is limited by 1D graphics and controls.  It is just two line segments (1D) hitting a dot (0D), and you can only move up or down (1D).  This is very similar to how the NES is limited by 2D graphics and controls.  There isn't much 1D or 3D in NES games.  It as pure 2D as you can get. (Some late games had parallax scrolling.  That's about it.)  The SNES is also considered a 2D system, but it is starting to push the envelope into 3D: crude games like Star Fox, character models like Donkey Kong, and tons and tons of parallax scrolling.  It's trying to push into 3D, but it's still very limited to fundamentally 2D graphics and controls.  The Atari 2600 is very much like this with respect to 1D.  It really is trying to push into 2D, probably even more than the SNES is pushing into 3D, but so many games are limited to line segments and dots, 1 dimensional graphics.  There are also plenty of games where you can only move left or right, 1 dimensional controls.  It's trying hard to be 2D, but there are still lots of 1D limitations on the games.

Graphics are not really 2D until you have an interior though.  One big reason that Dragon Quest became popular was because of the art of Akira Toriyama, who also created Dragon Ball.  The NES was the first system where his art could have been relevant.  NES characters had an interior and that allowed him to make all of those Dragon Quest creatures that are still used today.  His art would have been wasted on a system like the Atari 2600 where the characters do not have an interior, and he would most have had to work with something like stick figures or other crude shapes.  Graphically, an interior is a very important distinction.

You are thinking too literally.  If we are going to be that literal then there is no 1D or 2D.  Everything in reality is 3D.  A sheet of paper is 3D, because it has thickness even if it is very small.  The TV screen is also 3D because the screen has a thickness just like the sheet of paper.

I am speaking in mathematical terms.  In mathematical terms, a dot has no dimension.  Like when you graph a point with (x, y) coordinates, the point is considered to have no dimension.  We have to draw it big enough to see it, but it is considered to have no dimension.

"Actually, I misspoke.  A dot has no dimension.  It is 0D.  In any math class, your teacher has to make the dot big enough for you to see, so it technically has a height and width."

Uhhhhhhhh...

A dot has dimensions. It doesn't just "technically" have length and width, it actually does have length and width. If something has length and width it is two dimensional.

A point does not have any size or dimensions, but a point is not the same as a dot. A dot is a tangible symbol that represents a point. 

The ball in pong is not a point. It's not even supposed to represent a point. A point is a location in space, not something that bounces around on paddles. 

Like the dot your teacher draws, the ball in pong has length and width. It is two dimensional. If it was zero dimensional, we could not see it. If you could somehow "hit" an object with 0 dimensions then that's some kind of witchcraft.

Likewise, the paddles are not line segments. A line segment is a series of points. Theoretically, a line segment would have no width, but we cannot actually draw something with zero width. The thing that we do draw (which confusingly is also called a line segment) has width. 

The paddles in pong again aren't even an attempt to represent something with zero width. Those babies are thicc. They clearly do not have zero width.

They are made of four line segments. There is an interior space between the line segments. The fact that the interior is the same color as the sides does not mean there is no interior. They are rectangles. They have two sets of parallel sides that are equal in length, and four right angles.

The ball and the paddles all have length and width. That is evident based on the fact that we can see them. I can measure the area of all three. They all take up a definite amount of space on the plane. They are all two dimensionals.

I would indeed absolutely be shocked if a mathematician told me differently.

This post is purely a courtesy for your benefit. I'm not actually going to start arguing over whether something that we can clearly see takes up two dimensional space on a plane is actually zero dimensional.

You missed my entire point of my post, and i am not surprised coming from you.

I'm not into that dimension stuff, but a dot has to appear at least in 1 dimension in order to be recognised as a dot. 

Heh, you really want to tear this whole 1D/2D thing apart with a fine toothed comb.  I am just applying the same standards to the 1D/2D distinction as the 2D/3D distinction.

If I am going to understand where you are coming from, then I need to know how you define 3D gaming.  Most people mean Generation 5 games like Mario 64.  But 3D doesn't really mean 3D in every way.  The screen is 2D.  It is not like the 3DS or a VR system.  Also, an analogue stick is not even a fully 3D controller.  It's just a more precise 2D controller compared to a d-pad.  The analogue stick doesn't move in 3 dimensions.  The Wii remote is actually a 3D controller, because we can move our arm in 3 dimensions.  On top of this, the vast majority of PS1 games did not even require an analogue stick.

Do you consider Generation 5 to be the 3D generation?  If so why?  I consider graphics and the analogue stick to be the changes.  Is there something I missed?  It should be clear that 3D does not mean 3D in every single way.  It is more about the types of shapes that are drawn, how the shapes interact with one another and to a lesser extent the change in controls.

It should also be clear that we are talking in mathematical terms and not pure reality terms.  2D does not exist in pure reality.  Everything in reality is 3D no matter how narrow/thin it may be.  That is why this argument, "we could not see a 1D object" argument is a nonsense argument.  1D and 0D exist in mathematical terms, just like 2D only exists in mathematical terms.  If we are talking pure reality, then there is no 2D either.  2D only makes sense in mathematical terms.