Ships are put together out of modules, and the layout of modules matters a great deal: everything on board is done by individual airsailors who need to run around, ferrying coal, ammunition, water and repair tools - and sometimes their fallen comrades.
You can command fleets of airships both against the computer and against other players across the Internet.
In addition, there is a single-player strategic mode, where you use your fleet to conquer city after city, unlocking new modules and bonuses with each of them.
The game has an authentic-ish system of heraldry where you can create your own coat of arms, and register it with the game forums as unique to you. Buying the early access release gets you all future updates up to the final release for free.