You could start with just the most glaring bits of faulty design:

AA guns that complete crap

Planes flying anywhere except normal height being invulnerable too all but manual AA fire

Consequently, planes can just fly right up alongside ships without getting so much as a scrape - very realistic.

Planes have so much health some need multiple direct hits - again, realistic...

Many games you spend half your time trying to shoot planes - because thats what everyone plays NAVAL games for after all

Many guns in the game have completely ludicrous firing arcs, so as well as being underpowered compared to BBs, unlike BBs you haven't a chance in hell of hitting anything at your maximum range

Even logging into this site requires typing out some hidden letters - is this really such a high profile site for hackers and bots? Please get rid of it and save your actual players a lot of bother

The spread on guns, can be huge - why? Why not adjust the angle so they fire at a fairly concentred points regardless of the range, you know, angle them? When you press E to narrow your angle, why not make that stay as it is until you manually widen it, instead of the second you move your target? Makes it completely useless for anything but a stationary duel.

Sonar - what more need be said... why not change it so it actually works?

Forget new games modes and maps, please get these very basic things fixed as they spoil so many games.