You'll only be able to say that you created the perfect tower if it can withstand any attacking force in any scenario imaginable.
Therefore, you have to test your tower in different regions against waves of different enemy types.
The tower gains experience by destroying attackers, with which modules installed inside the tower can be upgraded.
The tower used for the test will be replaced by a new one at the end of the test (round), and all experience won will be lost. But don't worry!
Testing also provides resources to unlock and upgrade modules in your town.
As soon as you build a workshop you will also have the option to change the blueprint for your tower and the installed modules.
When you start a new round enemies will start approaching and attacking you from fixed locations.
Your tower will automatically retaliate against the attackers based on the modules installed in it.
Each time you destroy an enemy they will reward town resources and xp.
It is important to invest your xp to upgrade modules on the left side of the screen.
Eventually your tower will break and the round will be lost. (Nobody can start out perfect.)
Losing is part of the process of getting stronger. Now that you have gained some town resource you can upgrade the your modules inside the workshop.
For each round played you also gain some town xp.
When you reach a certain amount of xp your town will level up and you get a skillpoint which you can use to purchase skills that improve building's functionality.
There are two ways of upgrading your modules:
You gain xp for destroying enemies that can be used to improve your modules during that round. After a round is completed all modules reset back to the state they were in before the round was started.
Modules can be permanently upgraded inside the workshop.
This means that they start with a higher level when you start a new round.
Your tower needs to work in any environment and that's why you need to test the strength of your tower in different regions.
When you select a region, you will see a infographic displayed like the one above.
The percentage in the top left represents enemy difficulty. The square in the top right represents your highest wave.
Lastly the bar on the bottom represents the elemental properties of the enemies you will encounter.
The region can be changed by clicking on the map preview seen below:
Notice it says region 1, there are 15 regions in total for you to unlock and test your tower in.
To unlock a new region, you need to beat the previous region with any difficulty on normal mode.
Each region has unique enemy movement patterns, and in the future they will have special rules and effects, secrets and unlockable assets for your town.
An effort should be made to collect these as they will increase your power and give you options for loadouts.
Unlocking regions, and collecting then maxing modules will allow you to soft prestige. Soft prestige is done with the military, inside of the headquarters.
The normal mode allows you to test your tower against the environment in the given region.
Once you complete 100 waves in this mode, you unlock the Challenge, Endless and Idle Mode for the given area as well as the normal mode for the next one.
Same rules as the normal mode except there is no wave cap.
Challenge mode is not in the game yet. It is a special mode with certain rules to make the region a lot harder.
You play through it just like normal mode. Once complete it calculates your average resource gain.
This unlocks a no GFX mode, where you simply produce resources depending on your average.
When you select idle mode again, a button appears on the bottom left you can click to start your idle gains.
Sandbox can currently be unlocked on any region by beating normal impossible.
Currently sandbox mode has 2 customizable gameplay options.
1. The hp/damage scaling can be changed to match any difficulty on that region.
2. Clicking on the elements will toggle which elements enemies can spawn as, if no elements are selected, then by default every element will be enabled.
Sandbox mode has many more planned features that will be added in future releases of the game.
The difficulties control the rewards, and the strength of enemies.
Each difficulty has to be unlocked by beating the previous tier of difficulty, difficulty options have to be separately unlocked for each region.
Elemental resistances are increased in the higher difficulties.
On impossible, universal cubes and the remaining elemental cubes are added regardless of enemy composition.
In the future, the difficulty might also influence certain rules regarding the gameplay or the environmental effects and bonuses.