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Guidebook — Build Mods with C#, Lua, and JS

A hands-on guidebook that takes you from zero to a published Data Center mod. Pick one track — Lua, C#, or JavaScript — and build the same kind of mod in each. More languages (Python, Rust, Go, C# scripts) are in preview: see Guidebook Next Languages.

Framework version: gregCore 1.2.3 · Game: Data Center 1.0.50.15 · Unity 6000.5 IL2CPP · Loaders: MelonLoader 0.7.2+ / BepInEx 6+ · License: Apache-2.0. Everything here is English-only.

Which track?

Section titled “Which track?”
Track Status You need You get Start
Lua Production, full API Any text editor Fastest iteration, REPL, hot-reload, full greg.* API Guidebook Lua 01 First Mod
C# Production, full power .NET 6 SDK World editing, custom Harmony patches, max performance Guidebook CSharp 01 Setup
JS Production, UI-focused SDK Any text editor + tsc for TS Toasts, Toolkit panels, F1 menu, settings, hooks via Jint — HotLoad in main menu Guidebook JS 01 Setup

Rule of thumb: fast iteration and game-state automation → Lua. Spawning, cable operations, custom patches, heavy logic → C#. You already think in JavaScript and want UI mods fast (panels, toasts, menus, settings) → JS (and read its limits first).

How the guidebook is organized

Section titled “How the guidebook is organized”

Each chapter ends with a checkpoint: something runnable you can verify in-game before moving on.

What you will build

Section titled “What you will build”

Every track converges on the same sample mod — ShiftHelper: it greets you with your balance, logs money changes, repairs broken servers on a timer, keeps a setting, shows a small panel, and cleans up after itself. Lua builds it with the full API, C# mirrors it with registry + panel + patch, JS builds it with toasts + Toolkit panel + settings (same feature, script speed).

Reference companions

Section titled “Reference companions”