So, I've been replaying Dungeon Keeper lately. I must have 200 hours in this game. I beat all the campaign and expansion maps last year with Keeper FX 0.4.0. This year with 0.5.0. I know a lot of tricks that I would like to share.
First off, yeah, Keeper FX is much harder than the original. Why? Because the AI is constantly slapping and casting Speed on their units when they are training, which makes them train much faster. Unless you're slapping and speeding up your units all the time, the AI's units are going to be at a much higher level. Simply put, the player usually can't keep up with the AI's micromanagement.
It's not very fun, honestly. Training units takes a lot of time, which means if you fall too far behind their units, you have to spend a lot of time doing nothing but training your units to stand a chance.
However, you usually don't have to. Here are some tricks and ways to cheese the AI:
1- The most important one, the one you need to know the most, is that you can sell traps and doors! Yes, you can make gold indefinitely even when a map is out of gold! This is game-changing once you know it. You should train Trolls (the best manufacturers) to level 4. That's when they learn Speed and double their manufacturing skill. Then put them to make traps. Orcs are also good manufacturers; train them to at least to level 5.
2- The second most important thing you want to know is that if you don't want a creature, you can just drop them at the portal, and they will leave your dungeon, and another one to will appear.
The strongest units in terms of combat are Mistress >> Vampire >>>> Bile Demon >>> Orcs >> Dragons > Skeleton = Dog = Warlock. These are the units you can normally get through the portal. The other portal units are meh at best, so you should not bother with them. Mistresses are broken. Whoever has the most Mistresses wins. They get good at level 7 but become really broken at level 9, so it takes a while. Bile Demons are strong at level 4. Vampires are potentially the strongest at high level, but they're expensive and not easy to get. Usually, they are not worth it on most maps. Dragons normally suck, so you should not bother with them, with some exception I will talk about later.
To start getting them, you need:
Mistress - Torture Chamber
Bile Demon - a 5x5 Hatchery (just hold control when building it)
Vampire - A Graveyard and dead units for it
Dragon - Treasure Room at least 25 tiles, Lair at least 15 tiles
Orc - 9 tiles Training Room, 1 tile Barracks (which means you can drop 1 tile of Barracks anywhere, and Orcs will start appearing in your portal)
3- The third most important thing you need to know is that the enemy AI can't build bridges. This means if you're separated by water or lava, you're safe. The AI and Heroes (neutral units) cannot walk over lava either. There's a trap that creates lava called Lava Trap. If you build it on a corridor and the enemy triggers it, you're safe for the rest of the game.
4- When starting a game, the first thing you want to do is build a library and put the Warlocks to research. Warlocks are not strong in combat, but they're essential to research spells and rooms. Dragons are also good for this. Every time you get a unit, the first thing they do is go to the lair to build their home. You can speed up this process by picking them up and dropping them at the lair wait they build a home and then drop them at the room they should work in(and slap them).
5- Grenades are the cheapest trick in this game. Possess a unit that can use grenades - Orc LvL.9, Dragon LvL.3, Bile Demon LvL.7 - to possess them, hold control and left-click on them. You can spam grenades from range, and they do a lot of damage. You can pretty much kill all the AI keeper units and heroes by just spamming grenades from range. It's not very fun, so do it only if you really need to. The grenades also damage the enemy keeper's Heart.
When possessed by the player, Dragons are really strong, but without possession, they suck. The AI can't use them properly. They are also very expensive!
6- About the Horned Reaper, I usually don't bother with them. They get angry easily and are expensive. They get angry if they are not doing anything. You should put them on a Guard Post, so they will not get angry for doing nothing. If, for some reason, your Horned Reaper gets angry, build a small room of two tiles, lock it with a door, put the Horned Reaper and an Imp in the room, the HR will kill the Imp and gradually lower their anger level, the anger lower by standing near dead corpses. To Get a Horned Reaper, sacrifice Mistress - Spider - Bile Demon on a temple
Speaking of Sacrifice. to get a Mistress(the strognest unit) sacrifice 1 beetle and 2 spiders. Every Imp you sacfrice makes them cost less gold, if you sacfifice a lot you can spam a lot of Imps.
7- Room efficiency matters a lot. To achieve the best room efficiency, rooms should be square with reinforced walls. To reach 100% efficiency, you need a door as well. The higher the efficiency of a room, the faster the training, research, and capacity. You can see the room efficiency by the white bar displayed in your rooms.
8- You should reinforce walls to prevent Hero and enemy Keeper units from tunneling into your dungeon. To reinforce, pick up an Imp and drop it at a wall.
9- Traps are very effective against hero units. However, traps are usually not useful against AI keepers because they don't walk into your territory. There is one exception—the boulder trap. If a map allows you to build a boulder trap, you can easily win. The trick is to build a door, lock it, and construct a boulder trap behind the locked door. When the enemy keeper imp starts claiming your territory and reaches your door, drop a unit on them. The AI keeper will send all their creatures to attack your unit. Now, sell the locked door, and the boulder trap will annihilate their army. You can repeat this process as well. It's not very fun, but it's a valid way to win.
10- To prevent the AI keeper from training their units properly, possess a single unit and attack them. The AI will send all their creatures to attack your controlled unit and use the Call to Arms spell, their units will keep there doing nothing for a while, wasting a lot of time. You can repeat this process while your units are training, out leveling the AI Keeper units.
11- Samurai are the strongest hero unit, they are stronger than the Mistress.
12- When torturing a unit, the salary of all units of the same type will be halved. If, for example, you have many high-level Dragons, when Pay Day comes, pick up all your dragons, drop one of them in the torture room and quickly drop all the others near your treasure room. They will take half of the gold. However, do this quickly so your dragon does not get annoyed. You can also do this with Vampires, but Vampires instantly teleport to the treasure room when Pay Day arrives, so you have to place one in the torture room just before Pay Day.
13- To make your spell stronger, keep holding the left mouse button before casting it. The cost will increase, but so will the effectiveness. Usually, after casting the spell, the cost/effectiveness reset, making it unviable to do it during combat. However, there's a trick. When your units are fighting, you can view a battle reports by clicking on the flashing sword icon. The battle reports will display icons of the units involved in the battle, along with their current health. Click on the "heal" or another spell and hold the left mouse button to maximize effectiveness (costs 1200g). Instead of directly clicking on the units, you can heal them by clicking on their icons in the battle report. Here's the game-changing part: if you keep your cursor on the battle report without moving out of it, the cost and effectiveness will not reset. This means you can continuously spam maximum heal or other spells during a battle.
14- Warlocks get passive experience over time if the lair where they are sleeping to is built near a Gold tile. Dragons the same but with Lava tiles. Only if they're sleeping. Usually not usefeul but can save gold.
There are many other tricks I know, but this is all for now. I really like this game because there are a lot of obscure things you can do, i say emergent gameplay even.