Well, Pong is an arcade game from 1972, where you control a paddle and use it to bounce a ball past another, computer-controlled, paddle. Stereograms are these Magic Eye/SIRDS picture thingies, where you look at an incomprehensible picture with your eyes out of focus, and a 3d image appears.
3d stereogram Pong is a 3d version of Pong that you won't be able to play unless you keep your eyes out of focus. It's cool, it's stupid, and it will make your eyes bleed! Plus, it's not only a game - you can use it to paint your own stereograms!
Click on "New Pong game"; you'll see a trench that contains two paddles and a ball. The first few seconds, the ball will blink in an annoying way - then, it will start to move.
Move the bottom paddle using the mouse (recommended) or the arrow keys (bad idea), and try to bounce the ball past the computer-controlled paddle. Whenever someone makes a goal, the ball will blink for a few seconds, and then restart from the middle of the screen. The game ends when someone has scored 20 goals.
As in other Pong games, the ball follows its own peculiar rules: If the ball hits the right/left side of your paddle, it will bounce more to the right/left. If you're moving in the direction of the ball when you hit it, it will start to move faster.
On the right side of any moving 3d objects (like the ball or the paddles), you'll see a number of flat (non-3d) "echoes" of the object. I hope that's not too confusing; that's just the way stereograms work, and there's nothing I can do about it. Rely on your sense of depth, and you'll easily spot which ball/paddle is the real thing.
Click where it says "3d painter" to activate the painting mode, then hold down a mouse button and drag the cursor around on the drawing area. (You need to drag the mouse; just holding the button down won't work. Try moving it in really small circles).
Left mouse button adds height; right mouse button subtracts. If you have only one mouse button, you can toggle whether it will add or subtract height by pressing space (there's a small plus/minus sign to show you what you've chosen).
When you enter the painting mode, the screen will still show the title screen stereogram. Click on "Clear screen" or "Sine landscape" to change it.
Q: I've tried to look at stereogram pictures, but I have trouble seeing the 3d image. Can you give me advice about how I should look at the stereogram?
A: You should look just like you're looking now, only more bewildered.
Q: How did you create the program? Can I look at the source code? Can I use it on my site? Please?
A: I used anti-matter and tachyons. No. No. Go away.
Q: I played your game, and my eyes started to bleed!
A: That's normal. Stop whining, and play some more.
Q: I've tried everything, but I can't get 3d stereogram Pong to run on my computer!
A: I can live with that.