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Creating Your First Mod

This tutorial will guide you through creating a simple mod that modifies a basic in-game function.

warning

Although you will be writing the Mod in C#, remember that Dead Cells is written in Haxe and runs on the HashLink virtual machine, not the .NET virtual machine.

This tutorial assumes you have the following skills:

  • Basic C# programming
  • Basic Dead Cells mod creation (Tutorial)
tip

Before you begin, it is recommended to read the wiki to understand the basics of the HashLink virtual machine.

info

The mod code for this tutorial is stored on Github.

Creating the Mod Project​

  • Open your command-line tool.
  • Create a new class library project:
dotnet new classlib -n FirstDeadCellsMod -f net9.0
  • Navigate into the project directory:
cd FirstDeadCellsMod
  • Add a reference to the Dead Cells Modding MDK NuGet package:
dotnet add package DeadCellsCoreModding.MDK

Creating the Mod's Main Class File​

Create the mod's main class file, ModEntry.cs:

using ModCore.Events.Interfaces.Game;
using ModCore.Mods;

namespace FirstDeadCellsMod
{
    public class FirstDeadCells : ModBase,
        IOnGameExit
    {
        public FirstDeadCells(ModInfo info) : base(info) 
        {

        }
        public override void Initialize()
        {
            Logger.Information("Hello, World");
        }

        void IOnGameExit.OnGameExit()
        {
            Logger.Information("The game is exiting");
        }
    }
}

Configuring the Mod Project​

Edit the project file, FirstDeadCellsMod.csproj, and add the following content:

<PropertyGroup>
    <!--Mod Type-->
    <ModType>mod</ModType>

    <!--The FullName of the mod's main class-->
    <ModMain>FirstDeadCellsMod.FirstDeadCells</ModMain>

    <!--Automatically install the mod on build-->
    <!--<AutoInstallMod>true</AutoInstallMod>-->
</PropertyGroup>

Building the Mod​

Run the build command in the project directory:

dotnet build

After a successful build, the mod files will be generated in the bin\Debug\net9.0\output ($(OutputPath)\output) directory.

Testing the Mod​

  • Install the mod by following the tutorial.
  • Launch the game using DeadCellsModding.exe.
  • Check the game logs to confirm the mod has loaded.
info

You should see a log entry similar to this:

[13:47:52 INF][FirstDeadCells] Hello, World```

Common Issues​

Q1: Build fails​

  • Ensure the .NET 9 SDK is installed.
  • Check that the NuGet packages referenced in the project are available.
  • Try cleaning the solution and then rebuilding:
dotnet clean
dotnet build

Q2: Mod doesn't load​

  1. Check that the name in modinfo.json exactly matches the folder name.
  2. Confirm that the class path specified in ModMain is correct.
  3. Check the logs for error messages.

Q3: Game crashes​

  • Check your mod code for any exceptions.
  • Try disabling other mods to isolate the issue.
  • Check the logs for detailed information.