Probably the having the two ships shoot each other thing, although I don't know how they would do that. I would also like to make certain ships that can ram things and cause HUGE amounts of damage, but just make them barely maneuverable or something, so they would have to pretty much have a straight shot.
And then I would like to capture enemy ships, perhaps have an option to send it hurtling off somewhere to ram another ship. If it missed, I suppose I could just go and get it again
That, and I would like to use the terrain to my advantage, as in setting traps, triggering landslides/avalanches, or things like that. I don't know if they will do that or if they will, but I think it might be nice.