Use the arrow keys to move your paddle. Don't let the yellow circle touch the red line. Each time you hit the circle with your paddle you get a point. As you survive for longer, it will get harder. The speed of everything increases and the paddle shrinks.
There are a lot of minor glitches, so don't bother posting them in the comments. If you see a major glitch you can mention it in the comments. This is only a simple game base, and I will make many more complex or harder games out of it. If you get an idea you can make based off of this game, feel free to remix it.