[HundertzehnGustav]

Question... how would one go and do a more hardcore subsim, where one man behind a screen has to steer an entire submarine?

SHIII * is about taking command of a sub, and as such is a pretty good simulation of it. Can be improved by adding systems and enabling options, of course. But a game it isnt - games can be played without any knowledge of the subject. Sims need some klnowledge before the player can taked control. Only Hardcore Sims such as certain flight simulations (and payware addons?) need you to read a handbook, and follow procedures for things to work.

and as a kaleun, you do not need to know the knobs and switches and levers to start a diesel engine...