To successfully defend your base you’ll need a good combination of defensive buildings, cannons, and walls.
The main difference between defensive buildings (with the exception of walls) is their attack radius. When you place or select a defensive building, you will see a circle around it. This represents its attack radius — the distance at which it will begin to attack enemies. So take the attack radius in consideration when planning an adequate defense for your base. Also, note that some cannons can only target ground units, while others can only target flying units. There are also those that can attack both ground and air units.
Walls are the basic construction unit for protecting key buildings on your base. Use them to keep your enemies at a distance while your cannons blow them to bits.
Don't forget to upgrade your walls to make them stronger!
The Siege Tank is a massive weapon. It takes a while to recharge, but when it hits, it deals impressive splash damage. A note of caution — do to not let your enemies get too close to your Siege Tank; these tanks are made for long-range attack, which leaves them with a 'blind zone' in their immediate vicinity where they cannot reach the enemy.
Set a trap for your enemy! This defensive tower is shrouded in a holographic disguise. As soon as the enemy approaches, the Mirage will attack it with electric bolts. Upgrading your Mirage unlocks more disguise skins, allowing you to set even trickier traps for your enemies.
This magnetic weapon deals huge damage to a single target. The Railgun can be set to one of two modalities: ‘Ground’ or ‘Ground and Air’. The first modality only targets ground units, dealing huge damage. The second one deals less (but still impressive) damage, but targets both air and ground units. Attack radius also varies between ‘Ground’, and ‘Ground and Air’ modalities. Note that the Railgun is the only weapon that needs to be charged with resources in order to fire. To charge your Railgun, select it and click the ‘Charge’ button.