🎮 Cities: Skylines 2 Mod Development

Welcome to my Cities: Skylines 2 modding workspace. I keep the PRDs for each mod concept here along with the CitiesRegional prototype.

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✅ Official Repo Notes

This repository is intended to be the official source repo for the workspace and mod projects.

We do not commit:

• Game installs / deploy targets (CS2/, data/, any BepInEx/)
• Large archives (*.rar, *.zip, *.7z)
• Build outputs (bin/, obj/)

See .gitignore for the full list.

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📑 PRD Index

#	Mod Name	PRD File	Complexity	Time to MVP
1	City Analytics	PRD-01-SaveGameAnalyzer.md	⭐⭐ Medium-Low	2-4 weeks
2	Transit+	PRD-02-TransitPlus.md	⭐⭐⭐ Medium	4-6 weeks
3	Zone Master	PRD-03-ZoneMaster.md	⭐⭐⭐ Medium-High	5-7 weeks
4	Traffic Contributions	PRD-04-TrafficContributions.md	⭐⭐⭐ Medium	1-2 weeks to first PR
5	Cities Together	PRD-05-CitiesMultiplayer.md	⭐⭐⭐⭐⭐ Extreme	6-12+ months

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🎯 Quick Comparison

By Learning Value

Best For	Recommended PRD
First-time modder	PRD-01 (City Analytics)
Learning game systems	PRD-02 (Transit+)
Open-source contribution	PRD-04 (Traffic Contributions)
Ambitious long-term	PRD-05 (Multiplayer)

By Impact

Highest Downloads Potential	Why
PRD-03 (Zone Master)	Mixed-use zoning is universally wanted
PRD-04 (Traffic)	Traffic is #1 player concern
PRD-05 (Multiplayer)	Game-changing if achieved

By Solo-Friendliness

PRD	Solo Feasible?
PRD-01	✅ Yes - Perfect for solo
PRD-02	✅ Yes - Manageable solo
PRD-03	⚠️ Maybe - Complex but doable
PRD-04	✅ Yes - You're joining a team
PRD-05	❌ No - Team required

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📚 Each PRD Contains

• Problem Statement - What user pain points does this solve?
• Goals & Metrics - How do we measure success?
• User Personas - Who are we building for?
• Features - Detailed feature breakdown with mockups
• Technical Architecture - System design, key classes, Harmony patches
• UI/UX Design - Visual design and interaction patterns
• Development Roadmap - Week-by-week plan
• Risks & Mitigations - What could go wrong?
• Dependencies - Required libraries and mods
• Definition of Done - When is it shippable?

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🚀 Getting Started

1. Choose Your Path

Read through the PRDs and pick based on:

• Your experience level
• Time available
• What excites you most

2. Set Up Development Environment

# You'll need:
# - Visual Studio 2022 or JetBrains Rider
# - .NET 6.0 SDK
# - Cities: Skylines 2 (obviously)
# - BepInEx installed in game

# Clone the mod template:
git clone https://github.com/Captain-Of-Coit/cities-skylines-2-mod-template.git
cd cities-skylines-2-mod-template

3. Start Building!

Once you pick a PRD, I can help you:

• Set up the project structure
• Write the initial code
• Debug issues
• Test features

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🔗 Resources

Resource	Link
CS2 Modding Wiki	https://wiki.ciim.dev/
Cities2Modding Discord	https://discord.gg/cities2modding
BepInEx Docs	https://docs.bepinex.dev/
Harmony Docs	https://harmony.pardeike.net/
Thunderstore (Mods)	https://thunderstore.io/c/cities-skylines-ii/

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📁 Project Structure

D:\mods\
├── README.md                    # This file
│
├── PRD-01-SaveGameAnalyzer.md   # PRDs
├── PRD-02-TransitPlus.md
├── PRD-03-ZoneMaster.md
├── PRD-04-TrafficContributions.md
├── PRD-05-CitiesMultiplayer.md
├── PRD-05b-RegionalPlay.md      # ⭐ Detailed Regional Mode spec
│
└── CitiesRegional/              # 🚀 WORKING PROTOTYPE
    ├── CitiesRegional.csproj    # Main mod project
    ├── README.md                # Build & usage instructions
    ├── src/
    │   ├── CitiesRegionalPlugin.cs
    │   ├── Models/
    │   │   ├── RegionalCityData.cs
    │   │   └── Region.cs
    │   ├── Services/
    │   │   ├── RegionalManager.cs
    │   │   ├── IRegionalSync.cs
    │   │   └── CloudRegionalSync.cs
    │   └── Systems/
    │       ├── CityDataCollector.cs
    │       └── RegionalEffectsApplicator.cs
    └── Server/
        ├── RegionalServer.cs    # ASP.NET Core API
        ├── RegionalServer.csproj
        └── Dockerfile

🚀 Ready-to-Build Prototype

The CitiesRegional folder contains a working prototype with:

✅ Complete data models for regional sync
✅ Cloud sync service implementation
✅ Regional manager orchestration
✅ Placeholder game hooks (ready to fill in)
✅ Simple REST API server
✅ Docker support for server deployment

To build:

cd CitiesRegional
$env:CS2_INSTALL = "C:\Path\To\Cities Skylines II"
dotnet build

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❓ What's Next?

1. Pick a PRD from the index above that matches the kind of mod you want to build.
2. Open the matching PRD file and skim the goals, features, and risks.
3. If you want to work on the existing prototype, jump into CitiesRegional/README.md and follow the build steps there.