Arma 3: Multiplayer Campaign Creation

A multiplayer campaign is a series of interconnected missions that follow a sequential order, creating a storyline that groups of players can enjoy together.

Key things that a multiplayer campaign will include:

• Interconnected sequential missions
• Centralized location of common mission files to save on storage space
• Utilises MPCampaignDisplay
• Missions can be selected in the hosted server mission selection menu

This article covers setting up a multiplayer campaign back end similar to how the APEX campaign works.

Mission Creation

If new to creating missions, it is advised that you ignore concerns about disk space and make each mission independent of the campaign mod. When you get more comfortable with how the file structure works, and have more confidence in your code, you can then move on to centralising common files. Debugging missions within the mod structure is much more annoying, especially if your code is more prone to bugs/errors.

Be sure you structure your missions with multiplayer locality in mind from the start. It is much more time-consuming to convert a single-player mission into a multiplayer mission.

Mission Description.ext

ⓘ

See Description.ext.

The following settings need to be present in each mission's description.ext file:

skipLobby = 1;

These are important for the mission to flow from each mission in a multiplayer setting.

Avoid lobbies so that the missions can flow from one to the next without hangups. If skipLobby is disabled, mission01 is finished, the game will bring up mission01's lobby again and will only move to mission02's lobby upon hitting the Esc key.

This means that missions should be structured with CfgRespawnInventory rather than using editor unit loadouts.

File Structure

Now that the missions are created, we can move on to the mod's file structure.

myModName
|--addons
	|--myCampaignAddon
		|--campaign
		|  |--missions
		|  |  |--myMission01.worldName
		|  |  |--myMission02.worldName
		|  |  |--myMission03.worldName
		|  |--description.ext
		|--data
		|--functions
		|--$PBOPREFIX$
		|--config.cpp

Red highlights indicate required files/folders

Green highlights indicate optional organization files/folders for shared campaign files

PBO Prefix

$PBOPREFIX$ is a file that sits in the root folder of an addon. If your mod contains multiple addons, you will need multiple $PBOPREFIX$ files. $PBOPREFIX$ is a namespace definition that tells the game the file path to navigate to your addon.

Examples of possible $PBOPREFIX$:

myModName\myCampaignAddon	<--- Used for this guide
z\myModName\myCampaignAddon

Please refer to the documentation on the addon packer of your choice.

• HEMTT (Recommended): for repository-based mods
• PBOMan3
• Arma 3 - Addon Builder

Campaign Description.ext

ⓘ

See Campaign Description.ext.

Location: "\myModName\addons\myCampaignAddon\campaign\description.ext"

The campaign description file will dictate how the missions are structured within the campaign menus. Unlike a single-player campaign, we are going to be ignoring the mission flow aspect of the campaign description file so that the multiplayer campaign menu functions correctly.

/* --------------------------------------------------
	Defining Templates for Inheriting Later
-------------------------------------------------- */

// Setting up no endings, cutscenes, or rewards (stuff for single-player campaigns).

class NoEndings						// For use in chapter class and class MissionDefault.
{
	endDefault = "";
};

class MissionDefault : NoEndings	// For use in individual mission classes.
{
	lives = -1;						// Not important with/without "Tickets" respawn template.
	cutscene = "";

	lost = "";
	end1 = "";
	end2 = "";
	end3 = "";
	end4 = "";
	end5 = "";
	end6 = "";
};

/* --------------------------------------------------
	Actual Campaign Class
-------------------------------------------------- */

class Campaign									// Contained inside CfgMissions - Holds other campaign classes such as "Apex", "Bootcamp", "EastWind".
{
	firstBattle = "Missions";					// This will point to class Missions below which contains no information on purpose
												// so that the mp campaign menu will load all missions.
												// If info is given, no MPCampaignDisplay will be created.
	name = "$STR_CAMPAIGN_TITLE";
	briefingName = "$STR_CAMPAIGN_TITLE";
	author = "Hypoxic";
	overviewPicture = "\myModName\myCampaignAddon\data\img\myCampaignOverviewPicture.jpg";
	overviewText = "$STR_CAMPAIGN_DESCRIPTION";
	disableMP = 0;								// Set to 0

	class MyCampaign : NoEndings				// Chapter class - Typically only use one chapter when dealing with MP Campaigns.
	{
		firstMission = "myMission01";
		name = "$STR_CAMPAIGN_TITLE";
		cutscene = "";
		end1 = "";

		class myMission01 : MissionDefault		// Mission class - Inherits default settings from class MissionDefault above.
		{
			// Custom Endings - Defined in mission's CfgDebriefing
			myCustomEnd = "myMission02";

			// Default Endings - end1-6 inherited from MissionDefault class
			endDefault = "myMission02";			// defaults to when no other ending is defined - to prevent game crashing
			end1 = "myMission02";				// can override inherits from MissionDefault
			lost = "myMission01";

			template = "myMission01.worldName";
		};

		class MyMission02 : MissionDefault
		{
			endDefault = "myMission03";
			lost = "MyMission02";
			template = "MyMission02.worldName";
		};

		class MyMission03 : MissionDefault
		{
			endDefault = "";
			lost = "MyMission03";
			template = "MyMission03.worldName";
		};
	};

	class Missions						// This is essentially a class with empty values. Used to invoke MPCampaignDisplay - See firstBattle above.
	{
		name = "$STR_CAMPAIGN_TITLE";
		cutscene = "";
		firstMission = "";
		end1 = "";
		end2 = "";
		end3 = "";
		end4 = "";
		end5 = "";
		end6 = "";
		lost = "";
	};
};

⚠

An error in campaign's Description.ext WILL crash your game!

Config.cpp

Config.cpp will contain all of the top-level classes we want our mod to modify in-game. In our campaign's case, this will mainly be CfgPatches and CfgMissions

CfgPatches

class CfgPatches
{
	class MyCampaign
	{
		name = "MyCampaign - A Campaign That Campaigns";
		author = "Hypoxic";
		url = "https://arepublixchickentendersubsonsale.com/";

		requiredVersion = 2.10;
		requiredAddons[] = {		// Insert addons that your mod/campaign requires
			"A3_Functions_F"
		};
		units[] = {};
		weapons[] = {};
	};
};

If your campaign addon contains units/weapons/etc, add them to units[] and weapons[], just like you would with a normal mod.

CfgMissions

class CfgMissions
{
	class Campaigns
	{
		class MyCampaign
		{
			directory = "myModName\myCampaignAddon\campaign";
		};
	};

	class MPMissions
	{
		class MyCampaign	// Campaign class from above
		{
			briefingName = "$STR_CAMPAIGN_TITLE";

			class MyMission01
			{
				briefingName = "$STR_M01_MISSION_TITLE";
				directory = "myModName\myCampaignAddon\campaign\missions\myMission01.worldName";
			};

			class MyMission02
			{
				briefingName = "$STR_M02_MISSION_TITLE";
				directory = "myModName\myCampaignAddon\campaign\missions\myMission02.worldName";
			};

			class MyMission03
			{
				briefingName = "$STR_M03_MISSION_TITLE";
				directory = "myModName\myCampaignAddon\campaign\missions\myMission03.worldName";
			};
		};
	};
};

ⓘ

Directory must not contain a leading \

MPCampaign Display

Defining Values

1. Campaign Name - defined in either:
   1. CfgMissions.MPMissions.MyCampaign.briefingName
   2. Campaign description.ext: Campaign.briefingName
2. Mission Name - defined in either:
   1. CfgMissions.MPMissions.MyMission01.briefingName
   2. Mission description.ext: briefingName
3. See #2
4. Author - defined in:
   1. Campaign description.ext: Campaign.author
5. Mission Overview Picture - defined in:
   1. Mission description.ext: overviewPicture
6. Mission Overview Text - defined in:
   1. Mission description.ext: overviewText

⚠

Although child classes will precede their parents, it is best for the naming to be consistent.