Starting with version 1.3.8 the game now features an in-game level submission tool. It can be accessed by loading up any level you've made in the level editor, and either clicking on the "Publish/update/export level..." button, or by navigating to the "Level settings" menu and clicking on the "Export as mod" button located next to the menu close button.

From there on out you simply need to fill out all the text fields (or none, if the default setup suits you) related to the level setup, and you're good to go!
Simply follow the instructions and you'll be able to submit or update your level to the Steam Workshop!

It is highly encouraged to use this new utility to submit levels to Steam Workshop.
You can still manually set up a mod folder as per the instructions in this guide, but I encourage you to use the new tool instead. It's simple to use and straightforward.

Welcome! This guide will show you how to setup mods for uploading to workshop, how to create folders for local mods (in case you're testing your maps), as well as where to put levels in the game folder, to have the game load them.

Making mods, and maps, for Intravenous will require some basic Lua scripting knowledge to set-up map config files. Instead of manually setting it up, you can simply download the example single-level mod[www.dropbox.com], use the configs there as a base, delete everything that you don't need, and tweak the config files accordingly to your needs.
The same mod is also present in the game's "mods_staging/" folder, so you don't have to download it at all, if you wish to take a look at how a mod is set up. You can also copy-paste the mod there directly into the "mods" folder to have it load in the game locally.

You will need some kind of text editor with syntax highlighting, and I can personally recommend the following:

Notepad++[notepad-plus-plus.org] - good editor with simple syntax highlighting and indentation.
Sublime Text[www.sublimetext.com] - a really neat editor with more bells and whistles than Notepad++.

I don't think you'll need anything fancier, since the edits to the config files you'll be doing are going to be minimal.

You can access the level editor (or map editor) by clicking on the "Map editor" button in the main menu.
Despite the map editor being accessable only by opting into the relevant beta branch, subscribing to mods does not require this. At the time of publishing this guide, the game has been updated to support loading mods on the regular branch.

So if you see some cool-looking map on the Workshop that you want to try - go ahead and do so! There's no problem with that at all. :)

Maps you've subscribed to can be launched through the "Load map" menu. If the mod does not have a custom category that it's registered to, then it will be present in the "Miscellaneous" category at the bottom of the list.

Collapse the "Intravenous" campaign levels by clicking on the level category header.

The game can auto-load custom maps you've made. To do this, simply open the game's directory, and put the maps you want to be auto-loaded in maps/autoload/

Keep in mind, that in order to load the map, you will need to have a config file with the exact same name next to it. Usually the layout looks like this:


Setting up the config file requires some basic Lua knowledge. Thankfully, if you download the example map[www.dropbox.com], open the .lua files present there, and read the comments - it should be somewhat clearer.
Regardless, the autoload map config usually looks like this (click to enlarge!):


To be clear: auto-loading maps does not require you to make a separate mod, but it does require the map config file to be present.

If you follow the example mod above, and just modify the necessary fields to accomodate your own level - there will be no problems with autoloading a level, provided you place the map file and the map config file into "maps/autoload".

In order to publish a mod to Workshop, you will need to create a folder in the mods_staging folder, located in the game's root folder:


Inside that folder, you will need to have a sub-folder, called 'files'. Any image you place in the mod's root folder will be used for selecting the image to upload.


The 'files' folder itself should have 2 things
1. the 'main.lua', which is the entry point for every mod. If this file is not present, then the mod will not load. Luckily, the example mod present in 'mods_staging' that now comes with the game has everything ready, so you can use that as the base for all your mods! Be sure to take a look at the main.lua file, as it has very important information.
2. the 'maps' folder. You can place the map files into the mod's 'files' folder right next to the 'main.lua' file, but it's best to place the map files into a separate folder for organizational purposes.

Usually, it looks like this:


And the maps folder looks like this:


IMPORTANT NOTE: the maps placed in the example mod are not inside an "autoload" folder. That is because it's good practice to use the "autoload" folder to test your levels, and then to load them manually in main.lua, so that they appear in the proper order in the game's level selection menu, in the category that you've assigned them to.
Additionally, any maps found within the mod's maps/autoload/ directory will NOT be loaded. The autoload directory is only relevant to the root game folder, not the mods.

IMPORTANT NOTE 2: the map config file MUST be in the same folder as the map file itself, and have an identical name to the map file.

As mentioned before, the 'main.lua' file is the main entry point of the mod. Without it, the mod will not be loaded. The example mod main.lua file looks like this (click to enlarge!):


It contains very important information on setting up level categories, and various other info, so please be sure to read through it.

In order to test your mod, simply copy-paste the mod folder you've set up in the 'mods_staging' directory to the 'mods' directory.

If everything is set up properly, then it will be loaded in the game.
If you need guidance on how to set up the mod folder, please refer to the 'Preparing a mod' section of this guide.

In order to publish a map to workshop, you will need to start the game, click on the "Modding" button in the main menu, select "Steam Workshop", and click on the "Publish" button.
The mod submission guide in the game should guide you through the rest!

You will notice a list of tags to use for the mod you're about to submit, with only one of them being clickable - that's because the map editor update only supports level mods. More tags will be made available in the future!