Alternatively, we could at least have rocketry, basic incendiaries, etc. After all, while we're assumed to not allow going too modern, gunpowder is fucking old. Cannons, hand cannons, and to some extent matchlocks are also medieval as fuck. Just need to remember that "bulletproof" is a term that has its origins in the same era.
Well, regarding naval warfare wikipedia tell us that: From the late Middle Ages onwards, warships began to carry cannon of various calibres. The Battle of Arnemuiden, fought between England and France in 1338 at the start of the Hundred Years' War, was the first recorded European naval battle using artillery.
As for cannons in general: First invented in China, cannons were among the earliest forms of gunpowder artillery, and over time replaced siege engines—among other forms of ageing weaponry—on the battlefield. In the Middle East, the first use of the hand cannon is argued to be during the 1260 Battle of Ain Jalut between the Mamluks and Mongols. The first cannon in Europe were in use in Iberia by the mid-13th century. It was during this period, the Middle Ages, that cannon became standardized, and more effective in both the anti-infantry and siege roles.
However Toady, I recall, stated he doesn't like the idea of making firearms default into the game (obviously the game it's always open to mod them in). However I feel that cannons mounted on ships could be an exception. However purely mechanical artillery could do the trick on ships too.
Although I might be getting a little ahead of everything, at first we need at least a raft to move on the surface of a river or lake.
...as sliding roofs and other stranger stuff.
Well, how else is going to McXavier going to take out the dwarfjet out from the beneath the dwarfball court?