Steel Ocean is a free to play game on steam which is very similar to world of warships. so far it seems a little faster paced then wow, there are subs in this game and the night battles with the need of shooting flares to see the enemy was fun . very similar in most ways to wow, shooting a bit harder, graphics not as good but good. you get torps, a flak gun you aim and shoot, sonar and depth charges, a crew to lv up with perks. short of a full list of ships like wow, but growing. and more.
but what really makes this game is that you can set up a room for friends only, think up to 64, and have battles against friends! looks like you can invite or set up a PW, not very sure, just got started looking into it.