Getting started

A KCD:MP server is one program that the players’ games connect to. It runs one game mode - the rules of that server: where players spawn, what the chat and the commands do, who may hurt whom, what stands in the world. A game mode is a script or a plugin you write; the server calls it when something happens (a player joins, dies, types a command) and the script calls the server back (send a message, move a player, spawn a horse). A mode may also have a client script: its own half that runs inside each player’s game, for the things only the player’s screen can show.

Piece	What it is	Written in
The server	the dedicated server program, a folder you run on Windows or Linux: server.toml, the game modes, the data it keeps	-
A game mode	the rules of one server; one per server, reloaded without a restart	Lua or C#
A client script	the mode’s half on the player’s game: a marker, a sound, a bit of UI, a value read from the game; sent to the players by the server	Lua
The world data	the level’s tables, terrain, navigation mesh and collision geometry, exported from your own copy of the game	-

The server works out of the box: the two modes that ship with it, freeroam.lua and duel_arena.lua, are complete servers, and a mode that defines nothing is a valid mode - the server spawns everyone at its default point and answers its own chat commands. Everything on these pages is what you add.

The pages, in order

1. Setting up - the server folder, the first run, joining it, picking a mode, giving the server the game’s data, your editor. Step by step, whatever language you script in.
2. AI assistants - this documentation as plain text and as language-server definitions, and a CLAUDE.md that starts a game-mode project with a coding agent.
3. Server configuration - every key of server.toml, with its default.
4. Guides - one job per page: exporting the game’s tables, the terrain, the navigation mesh and the collision geometry from your game; putting a server on the public list.
5. The API for your language: Lua (the server and the client side, every callback and function on its own page) or C# (the same server API as typed interfaces).
6. The reference - the game’s lists: every item, soul, buff, mesh, preset, animation clip, door and container, by the keys the functions take.

Conventions

The same everywhere, whatever the language:

• metres in the level’s world space, as the game’s own console reports positions; z below 0 when spawning or teleporting means “on the terrain”;
• degrees for a yaw, 0 = facing +Y, counter-clockwise;
• 0xRRGGBBAA colours - 0xFF0000FF is opaque red;
• milliseconds for times and timers; the world clock in hours (13.5 = 13:30);
• a player is a pid (0 to the slot count minus one, reused after a disconnect); a world entity - a horse, a pickup, a prop, an NPC actor, a dog - is an id, unique while it lives;
• the keys of game things - items, souls, buffs, meshes - are an id, a name or a GUID from the reference; a call given an unknown key fails quietly (nil, false) and the server log says why.