Testing

A mod is loaded under Settings → Mods, and every way in ends in the same report: what loaded, or what is wrong, with the path into mod.json for each thing.

Loading a mod

• Open folder… is the edit loop. In Chrome and Edge the game keeps the folder open, so after you edit mod.json you press Reload on the mod's row and the change is in. Elsewhere, pick the folder again.
• Upload file… takes a zip of the folder or a .steel-tide-mod file (the manifest with the sheets embedded).
• Add from URL… and ?mod= take a mod served over the web: npx serve --cors my-mod and then open https://play.steelti.de/?mod=http://localhost:3000/. The mod is fetched again at every boot, so a page reload picks up an edit.

Seeing it in play

• The Open Range map has every unit and building on it already, yours included, so you can see the art and watch the guns without building anything. Your land and air defs are parked behind the motor pool, your ships out in the roadstead, and your buildings along the station road.
• The admin console has give <who> <unit> [n] for units, including a mod's units. Buildings are placed by an engineer.

In multiplayer

Mods work in local games and multiplayer rooms. In the lobby, the host or acting host selects installed mods under the title-bar gear → Mods, then applies the list. Everyone joining needs each required mod at the exact version named by the room. The game offers to install missing registry mods and reconnect; mods from elsewhere must be installed manually. A leader using an older registry version must update it before requiring it.

A save remembers the mods whose units, buildings or factions are in it; a match that only had a mod switched on saves and replays without it. Set the room's mods before loading a save that uses them, and the list stays fixed while that save is loaded.