- Ship models, variety in them, even more so by paints
- their handling, different with every model, and of course interaction with other models (combat with all animations/effects)
- their customization by upgrades, woods, port boni
- trading opportunities in the world, manifold. Not too easy but still nobody can go broke as long as eco missions remain as the last straw.
- fighting opportunities in the world, watching for appropriate opponents (and for PvP war server the need to avoid dangerous encounters)
- skill differences found in NPC captains. I have never seen anything like this in a computer game.