Fiefdom - Castle Defense & Economy - RPG Maker MZ

Fiefdom turns a plot of land into a system the player grows and defends across your whole game. Reward them with a fiefdom at the end of a questline, then let them build it up, run its economy, and hold it against bandits, monsters, and rival factions as the stakes escalate.

Two loops drive it, and they're linked:

Defense. Every structure contributes to a Defense Rating. Raids are repelled when your defenses meet the incoming strength — so the walls, towers, and garrison you invest in visibly decide whether the fief survives.

Economy. Economic buildings produce resources each cycle, multiplied by a rising Prosperity stat. Military buildings cost upkeep. Because a bigger army drains more than a small economy can supply, growing your forces forces you to grow your trade — a real tension, not two separate meters ticking up.

Features

• Built-in management menu — a ready-made scene where the player builds and upgrades. No hand-built menus required.
• Fully data-driven structures — define any buildings you like in the plugin parameters: name, cost curve, defense weight, income, upkeep, icon.
• Prosperity economy — income scales with prosperity, which grows on surplus, falls on deficit, and takes a hit when the fief is breached.
• Army upkeep — standing forces cost resources each cycle, tying your military size to your economy.
• Raid resolution, two ways — auto-resolve against your Defense Rating for quick raids, or feed the plugin's values into your own troop battles for set-piece defenses.
• Automatic breach consequences — a lost raid docks resources, drops prosperity, and damages a structure, all handled for you.
• Saves automatically — all fief state lives in the game's save file.
• Plugin commands and script calls for everything, so it drops into event-driven games cleanly.

What's included

• Fiefdom.js — the plugin.
• A step-by-step build guide that walks you through assembling a complete first castle-and-raid loop in the editor, from naming variables to your first battle.

Requirements

RPG Maker MZ. Standalone — no other plugins needed. (This is an MZ plugin and does not work in MV.)

Quick start

1. Drop Fiefdom.js into js/plugins/ and enable it.
2. Point its Resource and Defense variables at real variables in your project.
3. Put "Open Management Menu" on a steward NPC, seed some resources, and you're building. The included guide covers the rest.

FAQ

Does this work with RPG Maker MV? No — it's built for MZ. MV uses a different plugin API.

Do I need to know JavaScript? No. You configure everything in the Plugin Manager and drive it with plugin commands. Script calls are available if you want them, but they're optional. The included build guide assumes no coding.

Can I change the buildings, or add my own? Yes — every structure is defined in the plugin parameters. Add, remove, rename, and retune cost, defense, income, and upkeep however you like. Leave the list empty to start from a sensible default set.

How do raids actually play out? Two supported styles. The simplest compares your Defense Rating to the raid's strength and resolves instantly. The other feeds the plugin's values (like your watchtower level) into a normal RPG Maker battle, so upgrades become real advantages mid-fight. Both are covered in the guide.

Does the fief remember its state between play sessions? Yes. Structure levels, prosperity, and the day count all save inside the game's save file automatically.

Will it conflict with my other plugins? It's standalone and doesn't overwrite core battle or menu logic, so it generally coexists well. As always, place it after any core library plugins and test your specific stack.

Can I use this in a commercial game? Yes — free for commercial and non-commercial projects. Credit is appreciated but not required. Please don't resell or redistribute the plugin file itself as your own product.

Was AI used to make this? Yes — it was developed with AI assistance and written to RPG Maker MZ's plugin conventions. Questions and issues are welcome on the comments page.