I was initially going to allow the submarines in IHW: Pigboats to be from a range of countries - The UK, Germany, The USA, Japan, Italy, and the Netherlands, like I did the pilots in IHW: Aces In Spades and IHW: Aces And Angels. I have decided to forget about that. I may cover a nation at a time in supplements, if it comes to that, but for the released game I will focus on the US Navy and the Pacific war - the US subs were pretty much non-entities in the Atlantic.
Why? Because I can do some interesting things if the scene is limited. I can - for example - craft a mission generator with specificity, changing the locales offered as the war goes on, with new operating areas opening up and new forward bases established. I can make a generator for situations during the R&R period between missions. I can allow add-ons to the subs - the US subs were refitted after each mission with new and better gear. I can make a much better, more focused target selection. I don't have to account for the differences between the small Japanese convoys and the enormous Allied ones, or between Allied and Axis escort gear and tactics.
This is a pretty important decision for me. I've been agonizing over it for days, but it will be better in the long run, I think.