BTD6 Internal Structure

Some useful information about the internal structure of BTD6 so that you don't have to find it out yourself.

Game.instance

From any of your .cs files, you can use Game.instance to access the BloonTD6 Game. This class contains many important references to the data structures that power the overall running of the game.

The GameModel

Arguably the most important thing you'll find in Game.instance is Game.instance.model which is the main instance of the BloonsTD6 GameModel (but importantly not the only one). The GameModel isn't a model like a 3D display model, but rather a blueprint / collection of blueprints for playing a match of BloonsTD6.

For instance, for all the information about Towers, such as their behavior, cost, damage, etc are all held in TowerModels that you can find in Game.instance.model.towers. The GameModel contains various methods for finding TowerModels such as GetTower() and GetTowerFromId().

Similarly all the information about upgrades are stored in the UpgradeModels of Game.instance.model.upgrades, all the Bloons in BloonModels of Game.instance.model.bloons and etc.

InGame.instance

Similarly to Game.instance, you can use InGame.instance in any of your .cs files to access the InGame class which has a lot of important information and functions relating to running the current match of BTD6.

UnityToSimulation (aka the "bridge")

The UnityToSimulation class found at InGame.instance.bridge controls the interaction between the simulation (all of the information about the current state) and Unity (the engine powering the visualization of the game. This has more methods for handling / manipulating current match information, so if you didn't find what you were looking for in InGame.instance, this is another good place to look.

Also in this class InGame.instance.bridge.Model or (InGame.instance.GetGameModel() with our extension method) is another GameModel class. Read more to see why this is.

Cloned GameModels

The GameModel that can be found at Game.instance.model is in a pure / default state, effectively. It has all the TowerModels unmodified by Monkey Knowledge, all at their Medium difficulty price, etc.

When starting a new match of BTD6, the game makes a clone of this base GameModel, and then applies all the necessary modifications to it (the things that are referred to as "mods" in the source code). This includes things like Monkey Knowledge, Difficulty based pricing, CHIMPS rules, and more.

Thus, when making a mod, you as a modder need to decide which GameModel would be better to modify.

You can use the OnGameModelLoaded() hook in your BloonsTD6Mod file to change the core GameModel if you're doing something very important. This is dangerous, however, because other mods could implicitly rely on certain default functionality of the core GameModel.

The alternative is to use the OnNewGameModel() hook to modify the newly cloned GameModel whenever a match starts. This has the benefit of being safer with respect to other mods, as well as being able to interact with Monkey Knowledge and such. If you only sometimes want to make a change to the GameModel, this is definitely the way to go. Additionally, if we as a modding community ever want to get to the point where we can load and unload mods without restarting the game, this is the way we have to change the GameModel.