For invulnerability in this game, use the DOS utility DEBUG.
 First backup your game to be edited, then type the following
 from the dos prompt:

 ren e:\disk3.ovl cheater.cht
 debug e:\cheater.cht
 e 1ca7 7b
 e 96be 83 3f 00 7e 07
 w
 q

 Then rename CHEATER.CHT back to its previous name.