Let players connect

A player needs Kingdom Come: Deliverance II (Steam, GOG, or Microsoft Store / Xbox app), the client/ folder of a KCDC release, and your server’s address. The first part of this page is the checklist to send them; the second is your side: making the server reachable.

For players

1. Install. Unpack a KCDC release anywhere. Nothing goes into the game folder and no game file is modified.
2. Start Steam if you own the Steam copy. The launcher also detects Microsoft Store / Xbox app copies, including PC Game Pass. Without a saved game path, it tries Steam, then Microsoft Store, then asks you to select the executable. For GOG, pick Bin\Win64MasterMasterGogPGO\KingdomCome.exe; the Steam executable is under Bin\Win64MasterMasterSteamPGO\.
3. Launch. Run client\KCDCLauncher.exe.
4. Connect. On the KCDC menu, set your nickname, then pick a server:
   • Server browser: servers listed on the masterlist. A padlock marks one that asks for a password, typed in before joining.
   • Connect directly: host, port (usually 27015) and password. Leave the password empty unless the host gave you one.
   • Quick connect: 127.0.0.1:27015, a server on the same machine.

Use matching KCDC client and server builds. The browser can warn about a known version mismatch, and continuing may cause connection or gameplay problems. The launcher updates itself, so also check whether the server has been updated. See Server browser.

Unpack, do not copy

Unpack the full client archive with its dependencies. In 1.6.6, the launcher asks the update service which channel the installed build belongs to. The archive’s client\.mafiahub\channel is an initial hint, rather than a requirement that permanently decides future updates. A missing hint no longer blocks startup solely because the installation is unstamped.

The launcher remembers the game it found or was given in KCDC_launcher.json next to it. If the game moved, or the wrong copy was picked, delete that file to choose again. Launcher logs are in logs\ beside it. It needs the Microsoft Visual C++ 2015-2022 x64 redistributable, which the game installs.

Join with a link

The launcher accepts a server link and skips the menu:

In client/

.\KCDCLauncher.exe "kcdc://play.example.com:27015?nickname=Hana"

The format is kcdc://host[:port][?nickname=Name&password=Secret]; the port defaults to 27015 and the nickname to Player. Only the first menu visit uses it, so a disconnect returns to the menu.

Windows does not register kcdc://, so a clicked link does nothing. Give players a batch file next to client/ instead:

join-my-server.bat

@echo off
cd /d "%~dp0client"
KCDCLauncher.exe "kcdc://play.example.com?nickname=Hana"

What happens on connect

1. The client receives the level and required DLCs from server.json.
2. A player missing a required DLC is refused before any download: This server requires Legacy of the Forge, Mysteria Ecclesiae.
3. The client downloads every running resource’s client half and the custom assets it ships, loads the level and spawns. A first download larger than the player allows in the game’s Game settings (Ask before server downloads, 500 MB by default) waits on the joining screen for them to choose Download or Leave. Your scripts see playerConnect, then the spawn events (Join, spawn and respawn).

The game’s own loading screen stays up through all of this and lifts once the player is in. A server that admits the player but then stops answering for 10 seconds at any step is given up on, and the player is back in the main menu with the reason. The usual cause is a client and server on different KCDC versions.

A full server (512 players, or your lower maxplayers) turns the next player away.

Make your server reachable

Players need the game port (UDP) and should reach the HTTP port (TCP); the numbers are in Ports. Forwarding TCP for the game port does nothing, and a forward for the wrong protocol is the most common reason nobody can join.

• At home, behind a router: forward both ports to the server machine and allow KCDCServer.exe through Windows Defender Firewall on private and public networks. Outside players use your public IP; you and your LAN use the machine’s local address, since many routers do not loop the public one back.
• On a VPS or rented server: open both ports in the provider’s firewall or security group and in the OS firewall (ufw, firewalld).
• In a container: publish both ports and open them on the host (Docker and panels).

To test from outside, have a friend open http://your.public.address:27016/. A JSON page means the TCP forward works; if they still cannot join, check the UDP forward.

A player cannot connect

• With a Steam copy, is Steam running on the player’s machine?
• Do the player and the server run the same KCDC version? A mismatch often shows as a join that hangs on the loading screen for 10 seconds, then fails.
• Is the address right, and the port the game port, not the HTTP one?
• Is the game port forwarded as UDP, not TCP?
• Does the player have every DLC in mod.required_dlc installed?
• Is the server full?

Slow resource downloads

The loading screen reports the server resource download’s bytes and percentage. A download that keeps receiving data is allowed to continue even on a slow connection. Sixty seconds without new data ends the join with a message asking the player to check their connection and try again.

If this happens repeatedly, check the server’s resource delivery and the connection between it and the player. A large download alone is not a stall.

Related

• Run a dedicated server: ports and the status endpoint.
• Server browser listing: appear in the in-game browser.
• server.json settings: level, slots and required DLCs.
• Docker and panels: hosting in a container.