|Out of date.|
|It has been superseded by something that has been published elsewhere.|
Games that have a cardinality of gameplay that is 1D restrict movement to only one axis. This means that movement can only be controlled in one direction and the exact opposite of the direction. For example, up/down or left/right.
The player's ship is only controlled by moving left and right. While other buttons, L1, L2, R1, are used to control which notes are played when, they do not add an addition dimension to the gameplay because they do not change the orientation of the players avatar in the world.
In Pong, the player controls a raquet that moves vertically on the across the side of the screen. The object of the game is to position the raquet so that the ball hits it.
In Space Invaders, the player controls a ship that can move from left to right across the bottom of the screen. The objective is to fire at the enemy invaders that are slowly moving downwards.