A lot of World of Warships players have express feeling on the official website forums that commanding subs would be extremely boring due to the slow speed at which these boats move. It's a valid concern, but surface speeds of WW2 submarines tended to be between the Aurora and St. Lois. When submerged, they go about as fast as the Bogue or Langley. So, while slow they're no worse than ships already playable in the game. It's also important to note that sub commanders need not chase down targets, rather they can let their prey come to them.
I agree that coding U-boats (and the like) into the game engine might present some programming difficulties, but if you approach diving underwater like a destroyer's smokescreen then the challenge might be surmountable. The key differences are a diving consumable only affects the sub itself, has a countdown timer like the repair ability, and can be countered with acoustic sounding. Once underwater, subs depend on batteries (that run down based on how fast the boat is moving). Sitting still allows the sub to remain underwater longer, but makes it an easy target if located. Additionally, it's should be impossible to end a game in a victory or draw when underwater (more on that later). The inclusion of subs would also give destroyers (and certain cruisers) an expanded role in the form of anti-submarine warfare, not to mention new weapons like the depth charge and hedgehog.
Players start with cruisers at tier 1. From there can expand out to destroyers at tier 2, battleships at tier 3, and aircraft carriers at tier 4. Why not add subs at tier 6? It's at a place where destroyers start to lose their effectiveness against other surface ships. Here's a hypothetical example:
I want to toss out a few more ideas regarding subs. Instead of commanding a single ship, how about a single player controlling a "wolfpack" via an RTS-style tactical map similar to the one aircraft carrier commanders use. For such a player the pace of the battle might be more of a thinking-man's game, which might not appeal to everyone, but the same can just as easily be said for carrier gameplay. I think a couple of other restrictions also have to be applied to submarines for balance reasons.
- First, they can't capture (or prevent the capture of) bases while underwater.
- Second, destruction of all enemy subs isn't needed for victory (i.e. if one side loses all their surface ships then they are considered defeated regardless if they still have active subs on the map).
- Third, there needs to be strict limits on the number of subs in a given match (2-4 at most).
Of course, submarines aren't the only thing I'd like to see added to World of Warships. New nations and their fleets aside, minefields that offer some risk/reward in the crossing could be exciting. Night engagements with star-shells, spotlights, and lighthouse capture points would be great. A.I. controlled coastal defense batteries or P.T. boats would be awesome. Adverse weather conditions that affect visibility, speed and accuracy might be interesting too. There's a lot that could be added to the game. For me though, the number one thing remains submarines.