Making a game in The Modding Tree mostly involves defining parameters or functions on objects. If you aren't following the [getting started guide](getting-started.md), you should start by [setting up your basic mod info](main-mod-info.md) in [mod.js](/js/mod.js). It's important to set a mod id to ensure saving works properly.
Beyond that, the main way to add content is through creating layers, often in [layers.js](/js/layers.js). You can add new layers by calling `addLayer(layername, layerdata)`. There is an example of a basic layer in [layers.js](/js/layers.js) showing the recommended method. It is just an example and can be freely deleted. You can also use it as a reference or a base for your own layers.
Most of the time, you won't need to dive deep into the code to create things, but you still can if you really want to, for example to add new Vue components in [components.js](/js/components.js).
The Modding Tree uses [break\_eternity.js](https://github.com/Patashu/break_eternity.js) to store large values. This means that many numbers are `Decimal` objects, and must be treated differently. For example, you have to use `new Decimal(x)` to create a `Decimal` value instead of a plain number, and perform operations on them by calling functions. e.g, instead of `x = x + y`, use `x = x.add(y)`. Keep in mind this also applies to comparison operators, which should be replaced with calling the `.gt`, `.gte`, `.lt`, `.lte`, `.eq`, and `.neq` functions. See the [break\_eternity.js](https://github.com/Patashu/break_eternity.js) docs for more details on working with `Decimal` values.
Almost all values can be either a constant value, or a dynamic value. Dynamic values are defined by putting a function that returns what the value should be at any given time.
- [Custom Tab Layouts](custom-tab-layouts.md): An optional way to give your tabs a different layout. You can even create entirely new components to use.
- [Buyables](buyables.md): Create rebuyable upgrades for your layer (with the option to make them respec-able). Can be used to make Enhancers or Space Buildings, for example.
- [Clickables](clickables.md): A more generalized variant of buyables, for any kind of thing that is sometimes clickable. Between these and Buyables, you can do just about anything.
- [Bars](bars.md): Display some information as a progress bar, gauge, or similar. They are highly customizable, and can be horizontal and vertical as well.
- [Particle system](particles.md): Can be used to create particles for visual effects, but also interactable things like golden cookies or collectables.
