Creating your own in-game mod options is very simple. All it involves is creating fields using ModSetting(thing) classes in your Main BloonsMod class instead of regular data types, and just using them as values like normal in your code.

Any ModSetting(thing) class is created with a default value to use. They also all have a displayName that you can set, which by default will just be the name of the Field that you're assigning it to.

Also, all mod setting classes use a cool C# feature called Implicit Operators. This means that C# will be able to automatically convert them into the types they represent without you having to do anything.

But, in the couple situations where that won't work, you can always use their GetValue() method.

New with 3.0, ModSettings can also be given an icon and a description that will be shown. You can also specify requiresRestart to make it visually apparent that a setting's affect only applies after a restart.

For further customization, there's also a modifyOption parameter you can pass a function in to that will let you manually change the visuals, maybe with the new custom UI features.

The onValueChanged field can be used to cause side effects while the setting is being edited in the menu, or onSave for when the value is saved upon leaving the menu. customValidation can be provided to prevent the saving of invalid values.

A ModSettingInt represents a setting for a whole number. You can specify the minValue and maxValue if you like.

You can also set isSlider to true to have the setting display as a slider instead of a text entry. If you do this, you must set the minValue and maxValue options.

The exact same as ModSettingInt but allowing for non-whole numbers like floats and doubles.

A ModSettingBool can just be either true or false. You can use button bool to make it display as an enable/disable button instead of a checkbox.

A ModSettingString holds a string, obviously. You can use characterValidation to make the input box only accept certain characters.

A ModSettingButton defines an action that will be run when you press it. You can set the buttonText to be whatever you want.

A ModSettingEnum displays a dropdown of all the different values of an Enum type you provide it. A labelFunction can be provided to change how each enum name is displayed.

A ModSettingHotkey creates a customizable hotkey. You create it with a default KeyCode and optionally a modifier to go with it. The methods IsPressed(), JustPressed() and JustReleased() can be used elsewhere in your code to check if/how the hotkey is currently being activated.

ModSettings that let users open a Dialog Popup to select a file/folder on their computer.

A special type of ModSetting that you can define and then sat as the category property of other ModSettings. You can decided whether it should be collapsed by default or not, and can still give it a displayName and icon like all others. The order field can help you position the category in relation to other settings and categories.

public class Main : BloonsTD6Mod
{
    public static readonly ModSettingInt Cost = 500;  // implict operator in action

    public static readonly ModSettingDouble Range = new(50.0)
    {
        displayName = "Tower Range",
        minValue = 0.0,
        maxValue = 100.0,
        isSlider = true
    };

    public static readonly ModSettingBool SuperSecretSetting = false;

    public static readonly ModSettingString Message = new("hey")
    {
        characterValidation = TMP_InputField.CharacterValidation.Alphanumeric
    };

    public static readonly ModSettingCategory Version3Features = new("Version 3.0 Features")
    {
        collapsed = true
    };

    public static readonly ModSettingButton PushMe = new(() => ModHelper.Msg<Main>("The button was pushed!"))
    {
        category = Version3Features,
        buttonSprite = VanillaSprites.YellowBtnLong
    };

    public static readonly ModSettingEnum<MapDifficulty> Difficulty = new(MapDifficulty.Advanced)
    {
        category = Version3Features,
        labelFunction = difficulty => difficulty.ToString().ToUpper() + "!"
    };

    public static readonly ModSettingHotkey SomethingSpecial = new(KeyCode.F4, HotkeyModifier.Alt)
    {
        category = Version3Features,
        requiresRestart = true,
        icon = VanillaSprites.DangerSoonIcon
    };

    public static readonly ModSettingFolder HomeworkFolder = new("")
    {
        category = Version3Features,
        onSave = folder => DoSomeResearch(folder)
    };

    /* Can just use these values like normal in the code */
}