Getting Started with Modding using BepInEx

Install

• Installing Nine Chronicles at https://nine-chronicles.com/start

Verifying Nine Chronicles Operation (1st time)

• Launch the Nine Chronicles launcher and player to ensure they are working correctly.
• Close the Nine Chronicles player after confirmation. You may leave the launcher running.

Installing BepInEx 5 LTS

• Download BepInEx 5 LTS version.
  • https://github.com/BepInEx/BepInEx/releases/tag/v5.4.22
  • BepInEx_x64_5.4.22.0.zip
• Extract the BepInEx zip file into the folder where Nine Chronicles player is installed.
  • e.g., C:\Users{username}\Roaming\Nine Chronicles\player\main\
• After extraction, the BepInEx folder contains only the core folder at this point.

Verifying Nine Chronicles Operation (2nd time)

• Check if the Nine Chronicles player operates correctly with the default BepInEx installation.
• Close the Nine Chronicles player after confirmation.

Reviewing and Configuring the Automatically Generated BepInEx Structure

• Review the structure inside the extracted BepInEx folder.

• Open the BepInEx.cfg file inside the config folder to modify some settings.

[Chainloader]
  HideManagerGameObject = true
[Logging.Console]
  Enabled = true
[Preloader.Entrypoint]
  Type = Camera

Verifying Nine Chronicles Operation (3rd time)

• After modifying the BepInEx settings, confirm that the Nine Chronicles player operates correctly.
• Notice the difference with the BepInEx log terminal opening.
• Close the Nine Chronicles player after confirmation.

Developing Mods

1. Create a New dotnet Project
   • Target Framework: .NET Standard 2.1
   • Lang Version: 9.0
2. Add Basic Dependencies
   • Location e.g., C:\Users{username}\Roaming\Nine Chronicles\player\main\NineChronicles_Data\Managed\
     • UnityEngine.CoreModule.dll
     • UnityEngine.dll
     • Lib9c.dll
     • Nekoyume.dll
   • Location e.g., C:\Users{username}\Roaming\Nine Chronicles\player\main\BepInEx\core\
     • 0Harmony.dll
     • BepInEx.dll
3. Create a Plugin
   • To implement an example plugin, add additional dependencies
     • You can check example code here [https://github.com/planetarium/NineChronicles.Mods/tree/sample-dotnet-code/Sample]
     • Location e.g., C:\Users{username}\Roaming\Nine Chronicles\player\main\NineChronicles_Data\Managed\
       • UnityEngine.InputLegacyModule.dll

e.g., TestModPlugin.cs

using BepInEx;
using BepInEx.Logging;
using HarmonyLib;

namespace NineChronicles.Mods.TestMod
{
    [BepInPlugin(ModGUID, ModName, ModVersion)]
    public class TestModPlugin : BaseUnityPlugin
    {
        private const string ModGUID = "com.ninechronicles.mods.testmod";
        private const string ModName = "Test Mod";
        private const string ModVersion = "0.1.0";

        private static TestModPlugin Instance;

        private readonly Harmony _harmony = new Harmony(ModGUID);

        internal ManualLogSource _logger;

        private void Awake()
        {
            if (Instance is null)
            {
                Instance = this;
            }

            _logger = Logger.CreateLogSource(ModGUID);
            _logger.LogInfo($"{ModName} is loaded!");

            _harmony.PatchAll(typeof(TestModPlugin));
            _harmony.PatchAll(typeof(Patches.NotifyKeyboardInput));
        }
    }
}

e.g., NotifyKeyboardInput.cs

using HarmonyLib;
using Nekoyume.Game;
using Nekoyume.UI;
using UnityEngine;

namespace NineChronicles.Mods.TestMod.Patches
{
    [HarmonyPatch(typeof(ActionCamera))]
    internal class NotifyKeyboardInput
    {
        [HarmonyPatch("Update")]
        [HarmonyPostfix]
        private static void PostfixUpdate()
        {
            if (Input.GetKeyDown(KeyCode.Space))
            {
                NotificationSystem.Push(
                    Nekoyume.Model.Mail.MailType.System,
                    "Space key is pressed!",
                    Nekoyume.UI.Scroller.NotificationCell.NotificationType.Notification);
            }
        }
    }
}

Applying Mods

1. Build the Plugin
   • e.g., TestMod.dll
2. Copy the mod dll file to the Nine Chronicles player
   • e.g., C:\Users{username}\Roaming\Nine Chronicles\player\main\BepInEx\plugins\

Verifying Mod Operation

• After applying the mod dll file, check if the Nine Chronicles player operates normally.
• Confirm the mod is loaded properly in the BepInEx log terminal.
  • Loading [Test Mod 0.1.0]
  • Test Mod is loaded!
• Verify the mod operates as expected.
  • e.g., Pressing the space key triggers the 9c-unity NotificationSystem.Push() function.
• Close the Nine Chronicles player after confirmation.