[silhouette]

This is 1 big idea for fort variety which I will recommend stealing from other games like Majesty and Sim-${var}. Instead of having just a single all-or-nothing fortification plan for each nation, have an expandable design plan of forts available. Put them in lines of development, so if you buy a certain fort plan, you build type A, then you can later upgrade a fort type A to a type B by spending time/gold again, and then maybe to type C later. The nation design can still be important if you create different specialized lines of development (with A -> B-> C), which is what you buy at nation creation, instead of one fixed design.

I imagine it like this as an example: suppose there are 3 levels of each fort design, the initial level-1 and 2 levels of "upgrade". One nation wants to focus on high Defence, and buys a category of forts which has a lvl-1 Tower (admin10,def150), lvl-2 Fortress (admin15, def250), lvl-3 Citadel (admin20, def350). When you build a fort you get a Tower, then you can expand the Tower later into a Fortess (pay time/gold again, get +5admin,+100def), and if you want, then later expand to Citadel (pay time/gold again, ++ again). You can't upgrade to any other fort types, because these are the only ways you can evolve an existing design into a bigger one.

Another buys the "High Admin" design line which has these 3: lvl-1 Pallisade (admin30,def50), lvl-2 Walled City (admin40,def100), lvl-3 Fortified City (admin50,def200). Even if this nation expands a fort as big as possible, it will never have as good a defense as the first nations lvl-2 forts, but the admin is always way better.

Another nation (all you MP players) wants a fast-building fort, so they choose the Hasty-build line of designs which has lvl-1 Outpost (admin15, def0), lvl-2 Hold (admin20,def75), lvl-3 Stronghold (admin30, def150). This line of designs builds faster at each level, and is in between the first two in admin/def. As an additional penalty, the lvl-1 design has 0 defense (Ghost Rider vulnerable, insta-breach), so although it builds in only 2 turns it doesn't provide any protection until upgraded to a Hold.

Then there is the default line which costs the least design points and is in between the Citadel and Fortified city lines also (like the Stronghold), but builds in 3 turns instead of 2: lvl-1 Watchtower (admin20,def75), lvl-2 Keep (admin30, def150), and lvl-3 Castle (admin35, def250).

You can choose how large/sophisticated a fort you develop at each location, but it is still limited to the flavor you selected at the start. Largest forts take a long time and gold to build, but you only expand where you need it, and if you really need to defend a location you can do something more than just pile militia and summons into the fort. Imagine an attacking force coming to seige a Keep, and see it upgraded to a full Castle (extra def and supply) just as they arrive. Maybe a Pallisade province is taken by defenders just 1 month before the completion the Walled City, and then the seiged have to drive the attackers away just long enough to (continue) complete the construction.

Every nation starts with their level-2 as their home fort, so it is bigger then the lvl-1 forts they will start building elsewhere. But it still has upgrade headroom for later in the game or if they think there is an early rush coming and choose to beef up the home fort first instead of expanding with a new fort. Maybe require a lvl of construction research before being able to upgrade forts to lvl-3. It also provides another good investment to spend money on for those longer games where I always have extra cash.

You see... this is what happens when you stay up late reading about history of fortifications and how defences evolve at specific sites over time?

Sill