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:
aider.exe cheater.cht
 debug e:\cheater.cht
 e 1460 f8 c3
 e 920 90 90 90
 e 901 90 90 90
 w
 q
 Then rename CHEATER.CHT back to its previous name.