Whats up with this mission? Like 6 sewers right off the bat before you even build, not to mention bears and skels. How the heck you supposed to get started. They destroy everything I try to make and kill the builders.
Start with towers (minimum 2, maximum 4) between the sewers and upgrade them ASAP. It helped me to go through the first mins and after then the map is not so hard at all
You have a day or so before the sewers start spawning rats, so you'll want buildings that build fast. Ranger and Rogue Guilds build very quickly, Towers, Warrior and Cleric Guilds however don't.
This technique worked very well for me.Honestly, a lot of your starts sound expensive. What I did was much simpler. I didn't build a marketplace or any guilds, just four towers, one at each sewer grate. Just one each. And don't build anything else until they're done. You want the peasants to concentrate on the towers, not be distracted and spread out doing other things. Then upgrade each tower the moment it's built (By the time you're at four towers, upgrading the existing ones is cheaper than building new ones, and also WAY more effective).
Once you have four upgraded towers, the sewer grates and the Rat King are already dealt with. He'll never be a problem for the rest of the game. Just build your marketplace, save up money, and build guilds. Start with clerics, because they're the hardest to kill and you'll be dealing mostly with undead. Then build warriors.
The rest is easy.
I didn't know about the speed trick before I beat this mission, so I did it at normal speed.
I did it by building a Wizard's Guild first, then placing down wizard's towers to cover the sewer grates. Since they don't need peasants to build, they were actually completing, and I was able to scrape together enough gold to keep them running.
Once the constant rats etc. were kept at bay, I was able to start building guilds to recruit heroes, and go from there. It was a little slower going than typical, but it worked for me.