RUN SILENT, RUN DEEP (1K ZX-81)
by Rod Hopkins
from Your Computer (May 1983), page 78

[On 16K machines, type POKE 16389,68 followed by NEW before loading the game]

Keyboard decoding has been arranged to suit the destroyer skipper wearing
regulation Arctic-issue mittens: any key 1 through 5 will move the ship left,
while any key 6 to 0 will move it to the right. Pressing F releases a depth
charge. As normal, these devices are set to trigger at the supposed depth of
the submarine. This particular destroyer has excellent sonar; its charges
always go off at the appropriate depth. They must, however, drop into the
conning tower to produce the desired effect. To alter the speed at which
events take place, try Poking different values into address 16767.

[I've included a bug fix (originally put in by Greg) into the "Run Silent,]
[Run Deep" game to clear the screen before starting a new game.      PaulF]