If you pause the game and you should find that you are able
to move your gun target around.
For infinite lives in this game, use the DOS utility DEBUG.
First backup your game to be edited, then type the following
from the DOS prompt:
ren gitum.frm cheater.cht
e 3a6 c6 6 c0 85 c3 ff 2e 1f 0
Then rename CHEATER.CHT back to its previous name.