Gato
On the original ibm pc!! I used to play on level 7. Levels 8,9, you needed to know morse code to know what the mission was! I made timed maps of each mission, so I knew where to intercept the convoys.
Then, Silent Sevice on the pc and my friends c64 (which had better sound).
Red Storm Rising!
My all time favorite is SH1, commanders edition
