Before you launch the ball in the very beginning of the game enter the following codes.....

Code Effect

hidden test Control the ball using your mouse
gmax The gravity well should become enabled.
rmax You should advance one spot in rank. This can be done repeatedly until you get to the highest rank.
1max You should get an extra ball when you loose your upcomming ball
bmax You should have and unlimited supply of extra balls

After starting a new game, type in the code "hidden test" to play in debug mode.
Then hit these keys for the desired effect.

Code Effect

Y Changes the title of the game displayed at the top of the window from "3D Pinball for Windows-Space Cadet" to "pinball"
H Gives you a high score of 1,000,000,000, but always puts the score below the top highest legitimate score.
M Opens a box of the amount of memory currently used by the game.
R Promotes you to the next rank up.