Expansion packs

An expansion pack is new content made for the port - custom maps, fights and bosses, a level curve that makes level 99 worth reaching, quests and challenges, dialogue, trading cards, and game modes the original never had - that plays beside your own Legend of Legaia disc. It carries no game data: everything it borrows from the game, it names by coordinate, and the engine reads it off your disc. This page is the tour; the guides below it cover playing one, making one and playing online, and the format pages are the specification.

At a glance

What it is: A folder of TOML files (or one .lxpack file) the engine loads next to your disc. Nothing on the disc changes.
What it can add: Monsters derived from retail ones, formations with waves, bosses, encounter overrides, an XP curve and enemy scaling, quests, challenges, dialogue, trading cards and dealers, poker / Grid Duel / golf / racing / prop-hunt instances, custom maps with NPCs, props and entrances.
Where it plays: The native port (launcher or play-window --expansion) and the browser play page.
How it is made: By hand in any text editor, or on the expansion workbench in the browser.
Without a pack: The game as it shipped, bit for bit: every pack hook is the identity when no pack is loaded.
Example: Sample Expansion Pack, written with exactly the format and tooling any modder uses.

Play a pack

Load an .lxpack on the desktop or in the browser; entrances, the Journal, toasts and saves.

Make a pack

The workbench step by step, the files by hand, validating and bundling from the command line.

Play online

Host a world, walk a town together, sit down at poker, golf, a race or prop hunt.

A pack is not a ROM patch

The project has two ways to change the game, and they point opposite ways. The randomizer and disc patcher rewrite bytes on your copy of the disc, so any emulator or console plays the result. An expansion pack leaves the disc alone and adds to the port: it can do what no disc edit can - more enemies than a battle has seats, a map that exists on no disc, a poker table - because the engine is the one reading it.

	ROM patch	Expansion pack
Changes	Your `.bin` (or a `.ppf` beside it)	Nothing on the disc
Plays on	Any emulator or console	The port, native or browser
Bound by	Retail's code, sector sizes, free space	The engine's own limits
Shared as	A seed or a PPF	A pack folder or one `.lxpack`
Turned off by	Using the unpatched disc	Unload, or not loading it

Both share one rule: nothing that ships contains the disc's bytes.

Coordinates, not copies

A pack monster is always derived from a retail one: the pack writes base = { kind = "monster", id = 109 } and new numbers, and the engine reads that monster's mesh, textures, animations and attacks off your disc. A pack map names the retail scene whose scenery it reuses; an NPC names the retail placement whose model it wears; a card's portrait names the monster it shows. Each of those is a DiscRef, a coordinate into the disc.

Pack to coordinate to disc. The validator range-checks a coordinate with no disc at all; with a disc (in the engine, or on the workbench) it also checks that the coordinate names something real.

The validator backs the rule up: a file under assets/ must be a PNG, glTF, Ogg, WAV or plain text file and must not look like any disc format, and no file in a pack may be named like a disc file (the no-disc-bytes rule). That is what makes a pack safe to post anywhere.

What is in a pack

Every file but the manifest is optional, and every key in a file is optional: a pack writes only what it changes.

requiredpack.tomlid, name, version

fightsbattle.toml progression.tomlmonsters, curve

storyquests.toml dialog.toml cutscenes.tomlquests, lines, scenes

playcards.toml modes.tomlcards, modes

placesmaps/*.tomlone per map

own filesassets/png, ogg, ...

The pack as a directory, by what each file is for; as an .lxpack the same files sit in one deterministic archive.

The format

Layout, pack.toml, coordinates, the .lxpack bundle byte by byte, validation, cards and modes sections.

Battles and progression

Derived monsters, formations and waves, encounter overrides, bosses, the XP curve and enemy scaling.

Quests, dialogue and saves

Quests and challenges, pack dialogue on the retail dialogue runner, and the progress block a save carries.

Maps

Tiles over a retail base scene, corner-height tiers, props and NPCs, zones and entrances from the retail world.

Game modes and cards

Hold'em, Grid Duel, golf, racing, prop hunt; the card economy and its screens.

Netplay

Rooms and the relay, lockstep and host-authoritative sessions, roaming avatars.

How a pack reaches the engine

Both hosts end in the same call. The native window takes a pack folder or an .lxpack; the browser page takes an .lxpack (a file pick, or the bundle the workbench hands over). Each validates it - a pack with errors is refused, with the first few named - and activates it through SceneHost::activate_expansion_pack, which is World::activate_expansion: the battle tables compile, the XP curve swaps, the quest runtime adopts any progress a save kept for the pack.

Two hosts, one activation path. A save made with the pack keeps its progress in its own block, so loading it without the pack keeps that progress for later rather than losing it.

What a pack can do that retail cannot

Fights past the seat limit. A battle has four monster seats; a formation's waves bring more in as seats free up, and one victory pays for all of them.
A reason to reach 99. A banded or explicit XP curve, EXP and gold multipliers, and enemies that scale with the party past a level.
New places. A map painted tile by tile over a retail scene's scenery, with its own walls, heights, props, NPCs and encounter zones, reached through an entrance in the retail world.
New things to do. Quests that track retail story flags and the pack's own, challenges with scores, trading cards dropped in battle and sold at dealers, and five game modes - several of them playable online.

Start with the sample pack: load it, play it, then open it on the workbench and see how each piece is written.