When you say "realistic" keep in mind that the last "warshot" torpedo was launched in 1982 against the Gen. Belgrano. In modern times it doesn't happen often, although every Navy practices a lot.
A true Submarine simulation, IMO, should feature the world's best liberty ports and over-priced drinks.
Meanwhile, DW set a high threshold for game play back in the mid 1990's because you needed to be smart to beat it. You weren't making steam to run the turbines or learning how to live in state 5 seas or figuring out how many cans of beans you needed for an extended underway, but you got enough of the variables to play with and you could get a good feel for the daily grind of finding people who don't want to be found.
Which game is the best in terms of a true simulation? That's easy, none of them. You don't have to get used to breathing Amine or getting your quals finished for that long deployment next week. You don't have to know how to "stay sharp" when you've been awake for the last 20 hours or how to get your ### motivated four minutes after you were sound asleep. Life on a submarine is all about learning how to stack information and trust your buddies. Every day you're learning something new and ALL of it will be important at some point.
The good news is that your environment on the boat is, literally, your world and existence. People have asked me what it's really like living on a submarine and the best example I could use was to say, "Its just like Star Trek, either the original series or TNG, but with more swearing and less intrigue". They would look at me funny, but its true. Once you're ten miles off the coast you may as well be in orbit around Mars.
Now, I'm going to find a good seat in the corner and wait for the fights to break out.
