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).
- tooltip: **optional**. Adds a tooltip to this clickable, appears when it is hovered over. Can use basic HTML. Default is no tooltip. If this returns an empty value, that also disables the tooltip.
- showMasterButton(): **optional**. A function determining whether or not to show the button, if masterButtonPress is defined. Defaults to true if absent.
- branches: **optional**, This is primarially useful for clickable trees. An array of clickable ids. A line will appear from this clickable to all of the clickables in the list. Alternatively, an entry in the array can be a 2-element array consisting of the clickable id and a color value. The color value can either be a string with a hex color code, or a number from 1-3 (theme-affected colors). A third element in the array optionally specifies line width.