The controls are straightfowards once you know them but you have to find them first. There is a config manual that comes with the game but it only tells you some options. The rest you have to find on the internet or guess yourself. Here they are to make everyone else's life a little easier;

In Game Options
Start the game - Enter
Start with 1 to 4 players - F1 to F4
Change the view - 1 to 5
Toggle the Score Screen - L
Change the Opacity of the Score Screen - C
Pause the Game - P
Quit Game - ESC
Quick Exit - Left Shift + ESC

Actual Controls to play the game
Left flipper - Left Shift
Right flipper - Right Shift
Plunge/Fire - Return
Up Nudge - Spacebar
Left Nudge - Left Alt
Right Nudge - Right Alt