Cities: Skylines Modding on OpenMods

The city builder that became its own modding scene

Cities: Skylines (2015) launched with a deliberate strategy of mod-friendliness, Paradox and Colossal Order leaned hard on Steam Workshop integration and committed to engine stability for the better part of a decade. The result is one of the largest Workshop catalogues in PC gaming: hundreds of thousands of assets (buildings, vehicles, props), gameplay mods, and entire transit-infrastructure overhauls.

The mod scene has a defining feature: a small set of must-have mods that have effectively become an unofficial expanded base game (Move It, Network Extensions 2, Traffic Manager: President Edition, Find It). Almost every serious Cities: Skylines player runs them.

The toolchain

• Steam Workshop: the primary distribution channel.
• ModTools: community-developed debug interface, used by mod authors and power users.
• CSLModding.info wiki: community documentation hub.
• In-game Content Manager: toggle Workshop assets and mods per save.

What you'll find on OpenMods

Almost all Cities: Skylines mods live on Workshop. GitHub hosts source for the larger ones (TM:PE, Move It, Find It). OpenMods catalogues the GitHub-published mods, which are the framework-tier projects rather than asset packs.

Practical notes

• The "Big Four" are functionally required. Move It, Network Extensions 2, Traffic Manager: President Edition (TM:PE), and Find It! are installed in virtually every modded build. Most other mods assume one or more is present.
• Save game compatibility is mod-specific. Most well-maintained mods can be added or removed without save corruption. Asset removals are a different question, disabling an asset that's placed in your city causes silent removal.
• Performance scales with workshop subscriptions. Every subscribed asset is loaded at game start, even if not used in the current save. Players with 5000+ subscribed assets spend 5-10 minutes on game load.
• Cities: Skylines II is a separate game, separate ecosystem. Workshop-style content is replaced by Paradox Mods integration there. CS1 mods don't transfer.