This page is dedicated to the syntax modifications necessary to enable a scenario or campaign to work in multiplayer mode. Only the differences between multiplayer and singleplayer are are documented here, so you might want to read BuildingScenarios and BuildingCampaigns first.
Note: This page assumes you have a basic add-on set up as described in AddonStructure, as well as some coded content.
You can play standalone scenarios in multiplayer mode without setting up a campaign (this isn't possible in singleplayer). Simply make the following modifications:
- In the _main.cfg file, use #ifdef MULTIPLAYER as the load conditional
- In the scenario configuration file, use a toplevel [multiplayer] tag instead of [scenario] tag
Note: This section is relevant for version 1.11.6 and higher. A page about multiplayer campaigns on older versions can be found here.
Wesnoth has basic support for campaigns that can be played in multiplayer mode, with your friends, or even with an AI. There will still be some things that don't work as expected since some functionality for multiplayer campaigns is still being developed. While you can and should test your work in hotseat mode, there are a number of things that might behave differently under real network conditions (mostly affecting scenario and side parameters). Keep this in mind and make sure to test your campaign over the net, too.
The Campaign Tag
Multiplayer campaigns use the [campaign] tag, thus allowing the same campaign to work both in both modes. The only difference is that game also checks for a couple optional tags when campaign is used in multiplayer. They could be found on the CampaignWML page. Additionally, the type attribute should be explicitly set to mp or hybrid or otherwise a campaign would not be visible in multiplayer.
The Scenario File
A scenario in a multiplayer campaign is almost identical to a scenario in a singleplayer campaign. You only need to change the following:
- Every scenario which should not be available to start directly, should have allow_new_game=no inside the [scenario] tag. This will prevent it from showing as an "entry point" in the multiplayer configuration screen. (Version 1.13.? and later only) This is no longer true, allow_new_game=no is now the default
- For scenarios that don't use allow_new_game=no, one could make use of new_game_title to have a custom title. This is useful if the campaign is supposed to have multiple entry points such as chapters.
- Each human-controlled side needs to have a controller=human key defined in its [side] tag to work in network mode.
- Each human-controlled side also needs to have a save_id defined inside its [side] tag. Each side's save_id should be unique, and it should be the same in every scenario. Without this, your recall lists and leaders will not carry over from one scenario to the next. (Version 1.13.? and later only) This is no longer true, save_id defaults to id, just like in sp
- If you want to carry over information for ai sides, they need to have a save_id defined and persistent=yes in their [side] tags. (The same is true for singleplayer campaigns)
- (Version 1.13.? and later only) You can use previous_save_id to tell the engine which player shodul control which side. For example if you have a multiplayer campaign and in scenario1 you have two sides with ids Kalenz and Landar, and in scenario2 you have sides with ids Konrad and Delfador you can use previous_save_id=Kalenz and previous_save_id=Landar in scenario2 to make sure that the player that previously controlled Kalenz now controls Konrad and the player that previously controlled Landar now controlls Delfador.
- To ensure that your scenario settings won't get overwritten by the settings from the multiplayer configure dialog, you can set force_use_map_settings=true. However, if your campaign is not intended to be played strictly with default settings, you can set it to false.
- If any settings are still taken from the multiplayer configure dialog, it is possible to overwrite them in the prestart event. Useful tags include [set_recruit], [modify_side], [modify_turns],[remove_shroud], and [lift_fog]. You might also want to use experience_modifier=100 in the [scenario] tag.
When creating multiplayer content, you should be cautious of code that might change on one client but not the other players'. Not doing so can result in an Out of Sync error. Most [event]s are synced across all clients, but a few still have issues. A full list of safe events can be found on the EventWML page.