Submarine game.
Take control of a uboat U-48 and patrol the North Atlantic. Hunt Allied convoys and avoid escort groups. Return to Kiel bunkier to load torpedoes and upgrade your uboat.
Patrol report:
1203 Grid 42 Reached patrol area
2230 Grid 42 Ship spotted, bearing 080
2238 Grid 42 Visual contact, medium cargo ship
2243 Grid 42 3 bow torpedoes fired
2244 Grid 42 First explosion
2245 Grid 42 Second explosion, ship sunk

Rules on http://invertbit.blogspot.com/