Manual (German) [Source: Retro Commodore]
During play type "WHO IS THE BEST " press Right Shift and then the - (minus) on the main keyboard. Do not type in the double quotes, but make sure you press space after BEST. Once you press the - the blue background of the status/score bar will change to red. This will give you invincibility and infinite time. Your time and energy will continue to deplete, but you will not run out of time or die. Press 1-8 to skip to the corresponding level.
Use the following keys:
K - Toggle walk through walls and other objects
S - Toggle super speed
< - Toggle status bar with position information
E - Show Ending
T - Abort
DEL - Disable trainer
F10 - Kills the main guy for the level and adds 1000 to score everytime its pressed.
Backspace - ?
Source: Abaddon:
http://eab.abime.net/hol-contributions/59167-leavin-teramis-cheat.html