Relatively fast, free print-and-play minimalist convoys campaign game to keep Britain alive and build up for D-Day, opposed by U-boats, Kondor(/Vulture) etc. bombers, and the usual suspects: Scharnhorst, Bismarck, a pocket battleship, a raider, etc.
Half-year turns. NO GRID. }:-)
3 convoy lanes to lay out with 1 or more convoys per lane plus any escorting battleships or (escort) carriers.
Technology/operations advantage can shift from turn to turn.
Enigma (although there is no way to keep it secret from the German player. :-/ )
German Admiralty code breaking.
Murmansk Run.
Sudden death win, if the Allies get enough for D-Day in Summer 1944 or - for a 2-game-win Strategic Victory - even Summer 1943.
(24 shipfuls to be accumulated, but hungry Britons and visitors eat 2 each turn.)
Interesting to play solitaire, randomly composing the convoys and Atlantic patrols.
—description from the designer