Well, there's always Red October.
It'd be a kind of submarine commander simulator, only really any good for people who know what they're doing or are willing to learn some technical jargon and stuff.
However, my personal reccomendation would be: My stepdad reckons Red Storm Rising. I think maybe Red Rabbit.
What they REALLY need to do is make some games based on Matthew Riley's books. Ice Station would be truly, truly epic.