I finished this one on very hard yesterday. What I thought would be a fun and easy slugfest turned out to be very difficult. Partially due to confusion and patially due to solving the reason for the confusion. The 2 month spawns over the last 15 or so years that never end were very difficult to squash to meet the requirements and my first two attempts I kept thinking that something was wrong due to the fact that they never would end and if I felt they would overwhelm me. Then I read here that they were a part of the game so I made a new design to try to deal with the initial game and to finish off the spawns.
I couldn't handle the scale of the initial castle, so in all 3 attempts I tore down the castle after the initial battle and rebuilt. I rebuilt on the first attempt in a somewhat diagonal shape forming towers and walls along the river trying to use the river crossings as choke points and allowing for open building anywhere on my side of the river. This may have held, but I was still strung out and the incessant attacks were slowly breaking me down and exposing my flaws. So I abandoned that and as an experiment I closed in the signposts and pounded the enemy as they came on the map. This was working, but the enemy just seemed to never end and the fact that they started spawning at the same sign post every time right when I almost had them wiped out reinforced my thought that this was a glitch. So I read this thread and found out that it was part of the game.
So I did one more build using a gauntlet tactic. Sealing all crossings except the NE one. Setting up a wall going almost to the east edge to the south of the crossing and a line of towers and walls to the north. Funneling the enemy along this line and allowing access to the keep. On my side of the river I built mangronel towers to attack any siege builds across the river. I had to heavily reinforce the norhtern crossings to stunt these catapults from cutting a hole before I could destroy them.
This worked very well in the initial handling of the enemy. I used pitch and pits to prevent too many units from crossing the river. I kept a few crossbows on my side to deal with the few that crossed.
The economy was fairly simple. Reorganizing space and maximizing wheat space. Using all open dairy spaces. More than enough. Getting the quarries going. 3 initial and 5 after clearing trees Although I still bought massive amounts of stone for the closing battles. More than enough trees. I used woodcutters mostly to clear ground I needed to build on. Iron is not important unless you want to sell maces. Pitch was important for me until I got more than enough crossbows. I had enough space to get the religion requirement at a high 174 pop. before reducing. Buy hops and enough processing to keep pace was fairly simple.
The intermittent problems are a burden, but easy enough to deal with. The rabbits are very easy. The plague is bad enough to allow for multiple apothecaries if you want. I got lucky with the fire as it only hit some farms. I had protected the granary and armory, but it wasn't needed. And the thefts encourage a feeding level that keeps granary stocks down as much as possible.
I built a few archers and amped up my crossbows in each runthrough. Just build as many as you can keep pace with.
The finishing off was like a game within a game. I ended up going back to closing in the posts allowing them to still funnel into my NE kill zone. This took longer than the original time to finish. I built thick walls backed by ballista towers to do it. Cutting down new areas and blocking off areas so I could move my troops up safely and to prevent breakouts. When I finally was getting close I built up my good things very quickly and got the win.
I finally finished just short of 1150!
I had 20% troops lost.