Setting up Steam Workshop

Part 1 - Choose your Workshop type

Type	How it works	Good for
Ready-to-use	Items go live the moment a player uploads them. Subscribers get them automatically.	Levels, mods, blueprints. The default choice.
Curated	Players vote on submissions; you accept winners and typically integrate or sell them.	Official item pipelines, cosmetics with revenue share.

Enable it under Steamworks → your app → Community → Workshop → General. Pick the type, write the visible description, set up tags so players can filter content (e.g. Maps, Mods, Skins).

Part 2 - Upload code (creating items)

Most games ship an in-game uploader. With Steamworks.NET the flow is create once, then push updates to the same item:

using Steamworks;

// 1. Create the item (once) - returns the published file id
SteamAPICall_t call = SteamUGC.CreateItem(
    SteamUtils.GetAppID(), EWorkshopFileType.k_EWorkshopFileTypeCommunity);
// handle the CreateItemResult_t callback, store m_nPublishedFileId

// 2. Update content + metadata
UGCUpdateHandle_t h = SteamUGC.StartItemUpdate(SteamUtils.GetAppID(), publishedFileId);
SteamUGC.SetItemTitle(h, "My Cool Level");
SteamUGC.SetItemDescription(h, "A level I made.");
SteamUGC.SetItemContent(h, "C:/path/to/content/folder");   // whole folder is uploaded
SteamUGC.SetItemPreview(h, "C:/path/to/preview.png");      // shown in the Workshop UI
SteamUGC.SetItemVisibility(h, ERemoteStoragePublishedFileVisibility.k_ERemoteStoragePublishedFileVisibilityPublic);
SteamUGC.SubmitItemUpdate(h, "First upload");

Players must accept the Steam Workshop legal agreement (a one-time web confirmation) before their first item becomes publicly visible. Your uploader should detect the "needs agreement" result and open the agreement URL, or creators will think the upload silently failed. This catches almost everyone the first time.

Part 3 - Downloads (consuming items)

Subscriptions are automatic

When a player subscribes on the Workshop page, Steam downloads the item in the background to steamapps/workshop/content/<your-app-id>/<item-id>/.

Enumerate at runtime

Use SteamUGC.GetSubscribedItems to list what the player has, SteamUGC.GetItemInstallInfo to get each item's folder, then load the content with your own loader. Listen for ItemInstalled_t to hot-load items subscribed while the game runs.

Validate everything you load

Workshop content is user input. Never execute arbitrary code from items unless modding is explicitly your design, and sanity-check file sizes and formats before loading.

Scope advice: Workshop support is genuinely a retention multiplier, but it is a feature, not a checkbox. Ship it when your content format is stable, usually post-launch, and start with one item type.