The online game should be along the same lines as call of duty where you have 10 or so game maps and one side are in subs and the other side are in escorts guarding a convoy

Have 5 subs and 5 escorts in every online game and the subs can talk to each other and the escorts can talk to each other . How hard is it . Have the single player campaign game leaning more towards the hard core enthusiast and the multiplayer leaning more towards the casual shoot em up gamer . For the escorts just have a steering wheel , speed bell , depth charge button , star shells etc . In the sub have a simplified controls for the kids option or the same as in the campaign for the hard core enthusiasts . You would have 2 target audiences in the one game = more sales .