Frequently Asked Questions - CitiesSkylinesMultiplayer/CSM GitHub Wiki

This mod provides a Coop multiplayer experience for Cities: Skylines. You can build a single city together with your friends.

One player opens their game as a server and the other players can join.

You can directly install it from the Steam Workshop: https://steamcommunity.com/sharedfiles/filedetails/?id=1558438291.

For other platforms, see the next question:

Please follow the instructions on the homepage: https://citiesskylinesmultiplayer.com

Install and enable the mod in the content manager and then:

1. Create a new game or open an existing game (if using an existing game, make a backup!)
2. Open the "Pause Menu" (ESC)
3. Click the Multiplayer button on the top of the menu.
4. Update any of the fields to your liking, click Create Server.
5. Make sure other players can reach your game. (See the "Do I have to forward/open a port?" section below)

1. Click Join Game on the main menu.
2. Enter the server IP address and your information.
3. Click Connect to Server and wait up to 60 seconds.

Press the T key on your keyboard and start typing. For a list of commands, type /help.

To toggle the chat, press the T key on your keyboard or click on the Chirper icon.

The mod tries to open the required port automatically through UPnP. Additionally, it will use a technique called NAT hole punching to pass through routers and firewalls. This is used by many games and should work fine in most cases.

You can check if your game is accessible from the internet by opening the "Manage game" panel from the Multiplayer menu. If is not reachable, the host will have to manually port-forward the UDP port that was set in the Host game menu (defaults to 4230) on their router and possibly firewall.

An alternative to this is to use a proxy service like Hamachi, ZeroTier or Radmin VPN. Further troubleshooting guidance can be found in the following wiki page: Common issues

No, but if you encounter further issues you can try allowing Cities: Skylines through your local firewall.

The host can look up the local (when you're playing over LAN) or external (when playing over the internet) IP address in the Host Game menu. The clients need to enter this address to connect. When playing on Steam, you can also connect through the friends menu by clicking on "Join game". If you're playing over a tunneling service like for example Hamachi you need to use the IP address that is provided there.

There's currently no limit. But there could be more bugs when more than 2 players play together.

Please click here to view information on what is currently synced and not synced.

We now have an official modding API. This means that other mod's developers can implement multiplayer support. Currently, there is not much supported here, but assets should work fine. The mod will check that both sides have the same assets installed. A list of known supported (or partially supported) mods can be found here.

Some DLCs are already supported, others are being worked on. You can find the list of supported DLCs here. Just make sure that all players have the same DLCs installed/activated.

That means that your DLCs don't match ;)
You both need to have the exact same DLCs enabled, check in Steam to make sure that this is the case (Deluxe Edition also counts as a DLC!)

The CSM mod writes it's log data to %localappdata%/Colossal Order/Cities_Skylines/multiplayer-logs/ (on Windows). See Folder structure on where to find the Cities_Skylines folder on other platforms. You can also type /open-log into the in-game chat to open the current log file.

You can join our Discord Server: https://discord.gg/RjACPhd

Yes it is, you can donate at: https://www.patreon.com/CSM_MultiplayerMod

1. Did you enable the mod in the content manager?
2. Does the "Manage game" menu of the host show that the game is reachable from the internet?
3. If not, have you forwarded the port in your router (port 4230) and added an exception in your firewall (or use a VPN like Hamachi)?
4. Do you have the most recent CSM version (check with /version in the chat)?
5. Do you both have the same mods/assets/DLCs?
6. Are you using hamachi or radmin vpn? If yes, use the ip from those programs not the external given in the game.
7. Make sure that your firewall and anti-virus software allow Cities: Skylines to access the internet. Further troubleshooting guidance can be found at the Common issues wiki page.

1. Try to disable all other mods and DLCs
2. Try restarting the games
3. If it happens only sometimes, the client can type /sync into the chat to resync the game