Invincibility:
Note: This requires the three part floppy disk version of the game. Load the longest part of the game, then execute the following BASIC command to start the program. 

SYS 16384 

No opponents:
Load or reset the game, then execute the following BASIC commands before running or restarting the program. 

POKE 16805,169
POKE 16806,0
POKE 16807,234
SYS 5000