How replayable-4xish is this game?
 

To fill you in, I might just buy myself something to congratulate me on the exam which I think I just passed, and I am considering some of the Sharpnel games. This one in particular drags my eyes because I find the concept of sailship combat highly desirable. I am concerned on how lineal (or not) the game is, however. Personally, I´m addicted to 4x games. I know this is not a 4x per se, but I´m wondering to what extent it can generate random campaigns/scenarios/whatever, and hopefully have those be somewhat lasting.

For the record, I´m also looking at BCT commander, and Weird Worlds...

Re: How replayable-4xish is this game?
 

The campaigns are not linear. Most battles depend on how you perform and what 'area' you choose to attempt engagements in.
The game can be modded in most any aspect, so that you can make your own single battles or campaigns.

BCT and Weird Worlds are each a completely different type from each other.
Each game has it's own demo, and the demos give you a very good idea of what the full gameplay will be.