I thought I was done with tower defense, but playing Kingdom Rush dragged me right back in again. It's a crazy fun game, but it can be frustrating if you can't quite understand how to play. With that in mind, I've collected my top tips - with these tips for Kingdom Rush, you should find it easy to get 3 stars on every level.
Kingdom Rush Tip # 10: Survival of the Fittest
Many waves are positively full to the brim with weak enemies that go down without much trouble, but can easily bypass your soliders and slow-firing defenses. Thus, it pays to invest in towers early along the route that can thin these hordes out.
My go-to for this is the Bombard tower, specifically the Tesla x104 variant. With the Overcharge ability at max, it can easily take down any number of weaker enemies. It's also the best Bombard tower upgrade at taking down flying enemies like Gargoyles. Later levels have swarms of these flying enemies, and you'll be at an advantage if you've got a Tesla available.
In the later levels, typically the Bombard tower is my first to deploy, and my first to be upgraded. Sometimes I'll start the first round of a level with only a Tesla tower, and nothing else!
When placing a Bombard, try to find a location that has many locations after it (for other towers, which will take down stronger enemies) but is also relatively centrally located, so that most of your enemies will pass by it.
Kingdom Rush Tip # 9: Taking On the Toughies
Once you've thinned out the weaker enemies, it's time to focus on the harder, tougher baddies. These guys may take some damage from your Tesla towers, but chances are they're still going to need a strong finishing blow.
For this purpose there are two good Kingdom Rush towers - the Arcane upgrade to the Mage tower, and the Musketeer upgrade to the Archer tower. Both have abilities that can take down an enemy in a single hit - the Death Ray and the Sniper Shot, respectively.
You should place these towers after the Bombards, since you want them to focus on just the strong enemies. If you place them at the start, they'll vaporize a few of the weak enemies, but let the strong ones pass right by.
The Arcane tower's Teleport ability can also give you some additional time to deal with particularly tricky enemies that are threatening to overwhelm you.
Kingdom Rush Tip # 8: Support & Meat Shields
There are a couple of good support towers that mix well wherever you can put them in your defensive arrangement.
One is the Sorcerer upgrade to the Mage tower, which reduces enemy armor every time it hits. If you pair this with your Musketeers and Arcane towers, you can bring down even heavily armored enemies easily. If you grab the Summon Elemental ability, they can even slow down stronger enemies while your damage-dealing towers plink away at them.
The other is the Ranger upgrade to the Archer tower. Rangers fire extremely fast, but they can also poison and hold enemies with their special abilities. The poison slowly drains even the strongest of enemies, while the thorns ability gives your other towers more time to deal damage. They're also pretty good at taking down any heavily injured weak enemies that your Tesla towers didn't have time to kill.
You'll notice that I haven't even said a single thing about Militia towers. These towers can be somewhat handy in the early game, but the soldiers they train have a lot of disadvantages. There's only three of them, so they can't really stand up to a wave of weak enemies. With the exception of the Holy Order, they don't have enough defense or hit points to stand up to the stronger enemies, either.
Instead, my suggestion is to use your Reinforcements in place of Militia. Once you've sunk a few stars into the Reinforcements upgrade tree, they can hold their own against weaker enemies, and they can be deployed anywhere on the map - even to spots where you have no towers or are beyond the reach of any tower that could be deployed. At the max upgrade level, they can even throw spears at flying enemies, which means they can fill in in a pinch against almost any foe.
Kingdom Rush Tip # 7: Depth-First Defense
When you're just starting out on a level, it's tempting to try and fill all the tower slots with level 1 towers. However, level 1 towers in Kingdom Rush are pathetically weak, and don't stand a chance past the first few waves.
Thus, my suggestion is to focus on a few towers and get them powered up before you add new ones. Like I mentioned above, sometimes I start the first round with just a powered-up Bombard tower, since the first wave is usually weaker enemies. Then you can bring in a Mage tower and start upgrading it to either support (Sorcerer) or as a damage dealer (Arcane).
The types of towers you decide to focus on are dependant on what types of enemies the level features. Some enemies have high magic or armor defense. You can check by tapping on the enemy or visiting the Encyclopedia from the map screen. If a particular path or level features enemies with a higher defense against a certain tower type, you may choose to pick different types of towers to feature.
Kingdom Rush Tip # 6: Burn Early, Burn Often
Rain of Fire is the other special ability you have besides the aforementioned Reinforcements. You may be tempted to save this for emergency use only, but once you've sunk some upgrade points into it, you can use it pretty frequently.
Note also that calling a wave early shortens the timer on this skill and Reinforcements, although it's more useful with Rain of Fire since it has a longer cooldown.
I like to use this skill to "thin the herd" in early rounds when I have few towers up. It can also give you a gold boost to build or upgrade another tower in an area where you anticipate problems shortly.
The game advises you to aim a little bit ahead of an enemy, but I like to drop it on top of a group of enemies that is temporarily halted by my Reinforcements, Hero, or your soldiers if you have any.
Once you have the "Scorched Earth" upgrade, Rain of Fire can be quite useful against a wave of weaker monsters. It will persist for a couple of seconds, and can take weaker monsters even if they're at full health.