It is a sophisticated simulation for people who like their sims sophisticated.
Sub Command is the kind of game most publishers would be afraid to release. It is ambitious, complex, difficult to learn, and slavishly devoted to realism. You spend most of your time looking at control panels and wondering what's out there. There's a lot of waiting and guessing. The average gamer would hate it--but Sub Command isn't for the average gamer. It is a sophisticated simulation for people who like their sims sophisticated. If you're a hard-core simmer--the kind of person who revels in a meaty manual, who thinks relaxed realism settings just teach bad habits, and who scoffs at putting a 3D engine in Harpoon because you'll only be using NATO symbology anyway--then Sub Command has your name written all over it.
Sub Command was created by Sonalysts as a follow-up to its last submarine sim, Jane's 688(I) Hunter/Killer. 688(I) was easily the most realistic contemporary sub sim when it was released, but it was criticized for having canned scenarios and a linear campaign. Sub Command continues this trend, but there's more variability in the scenarios. Also, the campaign missions are interrelated, so your performance in one mission will have an effect on the setup of the next mission. It's not a dynamic campaign per se, but there's a sense of continuity. Since you can play the campaign and most of the scenarios from the US or the Russian side, there's more replayability than there was in 688(I). Furthermore, there's a comprehensive scenario editor, so expect to see plenty of player-made scenarios on the Internet.
The most immediate difference from 688(I) is that Sub Command lets you control your choice of four different subs: the 688(I) improved Los Angeles class, the next-generation Seawolf, or one of two variants of Russia's bulbous Akula. The controls range from the Seawolf's sleek touch displays and the 688's smartly military panels to the Akula's clunky spread of tickers, switches, knobs, and cranks. From the inside, these subs have a tremendous amount of personality. There are also differences in their weapon loadouts and sonar suites. However, it's hard to tell how much they differ in capability. The Akula and Seawolf are light-years apart in terms of technology. The Seawolf should be so quiet that it can cruise at relatively high speeds with little risk of detection, and the Akula should be a noisy clunker in comparison. But there's no indication of these differences in the game or manual.
Sub Command's manual is a 208-page Adobe Acrobat file. Be sure you've got a printer with plenty of toner, or about 15 bucks to print it out at the local Kinko's. Even then, the manual is only slightly helpful. It does a good job of explaining how you do things, but doesn't offer a whit of advice for why you should do things. There's no information on avoiding detection, evading incoming torpedoes, or how to best use your sensors. It's as if Sonalysts expects you to already know what you're supposed to do once you're in charge of a nuclear submarine. This makes the game's steep learning curve even steeper. There are three short tutorials that offer only basic information before suddenly ending, leaving you with more questions than answers. It's insulting enough that EA doesn't offer a printed manual; it's just pouring salt in the wound that such a big manual contains so little helpful information.
Once you get the hang of it, Sub Command is basically a hide-and-seek game with advanced electronics. In a contemporary sub, you're more of a high-tech detective than a warrior. Instead of fighting a battle, you're solving a mystery. Who's out there? Where exactly are they? Where are they going? Have they heard me? Should I shoot at them? You're putting together pieces of a puzzle, one shred of evidence at a time. Through patience and careful analysis, you draw conclusions and act accordingly.