Question
I've tried this scenario 7-8 times now and can't seem to survive for very long before all of my buildings get destroyed and I'm totally wiped out. The hordes of rats just get to be too much too quickly.
What is the optimal opening build order in order to ensure survival long enough to destroy some of the mob dens?
Answer
This map an unusual one. It starts with a lot of rat holes around your town, so you first have to defend from them. Follow this advices:
Build some heroes, not rogues, and not only archers, you'll need tough units at the very beginning.
Also build 2 or 3 towers, and place them between the most amount of rat holes possible, and upgrade them sooner than normal, they are the perfect defense as the game advances. I usually place buildings behind towers and very near the town center. As game advances and building basic towers gets too expensive, focus on dwarf towers.
Start exploring and attacking as soon as you resist the rat hordes easily. This is extremely important if you don't want to drown in future ranging hordes of big rats.
Upgrade your blacksmith forge and market. As soon as you see heroes having money enough to buy stuff, maybe 30 to 80 gold at the beginning, 150-200 at higher hero levels. They'll bring you money enough to make expensive building upgrades like the town center, a 2nd market, or strong towers.
Finally, when you attack the Rat King, remember to use your magic spells.
I can give you many more, but these are good to start the level in the right direction.
Also, you can watch these videos of people finishing it, they helped me a lot
For the rest of maps, the best advices for starting a map are... ATTACK, EXPLORE, UPGRADE. Don't focus on defense for a regular map. Be more aggressive in this game than you usually are in others.
Attack, attack, attack! Start with the nearest enemies, do it as fast as possible, so every starting unit gets leveled as soon as possible (prefer warriors, they are very tough when they get alone with an enemy). Only stop attacking on exceptional cases, while defending your castle, market or similar.
Explore at the same time you're attacking, with two or three archers at first, spend money if you need so, they will give you very valuable information of your next possible enemies, and map in general.
Don't spend much money on towers at the beginning, just to cover your back. Let units hold frontal town attacks, and focus first on toughest enemies (with money rewards).
If you find vampire yards, or other really hard units, erase them form the map before they start producing large amounts of unstoppable units.
Upgrade, don't forget it, you may be building enough units that level fast, but you didn't upgrade your forge and market, and you're getting money slowly, not letting your units buy better upgrades/potions as game advances. Keep them in mind, focusing your economy on the money coming from heroes buying items is almost essential at the late beginning.
Hope it helps!
Check more discussion of this question.
