Japanese subs are a must: think about it, you could start off in a two man midget sub or something and move up from there, then you could be a mother sub and fire midget subs or something. plus it would have a learning curve ex. going from the easy pre-US war days to the US-Japanese war, thus extending the war for you
New missions from HQ ex. attack the Panama Canal, raid Pearl Harbour, hunt other sub or ship etc. maybe add in secret missions ex. delivering atom bombs to Germany or testing out a new sub etc.
Fully set interior and crew, ex. I want to see my torpedo crew loading external torpedoes while on deck etc., I'd also like to see damage, so when water is pilling in through a hole in the engine room, i want to be there
Innovative online- play as cat and mouse ex. 1 team plays as the destroyers (or better yet cargos) and another as subs. However leave destroyers and such out of the single player.
Timed crew shifts.
maybe receive weather reports, and hurricanes
"News" system over radio when in port and/or out on the water (a la Starlancer)
better death sequence, i want to be in the sub till it implodes, and then watch her sink.
wolfpacks
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I was told we'd cruise the seas, for american gold, we'd fire no guns, shed no tears. Now I'm a broken man on a halifax pier. The Last of Barrett's Privateers.-  Stan Rogers |