Modding guide

Steel Tide takes mods. A mod adds units, buildings and upgrade levels, described in one JSON file with sprite sheets beside it if you draw some, and gives them behaviour of their own: forms they turn into, units they spawn, buttons on their cards, weapons that look like nothing in the game. The game lists mods under Settings → Mods, next to the official registry where everyone's mods are published. A mod cannot change the rules, the interface or the units the game ships with: it adds, and everything it adds is switched off with it. That is what keeps a mod safe to install and a save safe to load.

What a mod is

A folder:

my-mod/
  mod.json          the manifest: the mod's identity, its defs, and the sheets they draw with
  sprites/*.png     optional art
  screenshots/*.png the mod in play, 4:3; the registry asks for at least one
  README.md         optional

mod.json names the mod, then lists its defs (each a unit, a building or an upgrade level) and, if the mod draws its own art, the sheets. Every field a def can carry is a field of the game's own unit definition, so anything you can read off a wiki page is something a mod can set.

Each page of this guide ends with a reference: the fields its part of mod.json takes. Anything not in those tables is ignored with a warning; a number outside its range is an error.

Start with your first mod: a working one in five minutes. If you would rather hand the work to a coding agent, there is a skill for it.