There are several differences between the two. One is that a buyable's saved data is its amount as a `Decimal`, while Clickables store a "state" which can be a number or string, but not `Decimal`, array, or object). Buyables have a number of extra features which you can see on their page. Clickables also have a smaller default size.
- effect(): **optional**. A function that calculates and returns the current values of bonuses of this clickable. Can return a value or an object containing multiple values.
- display(): A function returning everything that should be displayed on the clickable after the title, likely changing based on its state. Can use basic HTML.
- style: **optional**. Applies CSS to this clickable, in the form of an object where the keys are CSS attributes, and the values are the values for those attributes (both as strings).
- layer: **assigned automagically**. It's the same value as the name of this layer, so you can do `player[this.layer].points` or similar.
- id: **assigned automagically**. It's the "key" which the clickable was stored under, for convenient access. The clickable in the example's id is 11.
You can also use these features on the clickables object to add a button above all the clickables, for implementing a respec button or similar.
- masterButtonPress(): **optional**. If present, an additional button will appear above the clickables. Pressing it will call this function.