MRPGI/games

Games are folders. Lore is JSON.

Every MRPGI game is a folder you can zip, share, hand-write, or have an LLM generate. This directory holds examples; lost-fuse/ is the guided one — three rooms that demonstrate every mechanic the engine has, in one small puzzle chain.

Play it

cargo run -p mrpgi -- --game games/lost-fuse          # in the GUI
cargo run -p mrpgi-core --bin mrpgi-headless -- --game games/lost-fuse   # in a terminal, JSON in/out

(Spoilers below — play it first! It's five minutes.)

The anatomy of a quest

The whole game is ~200 lines of JSON. The chain:

take fuse                    an item        →  inventory        (room 0)
use amp                      needs: fuse    →  sets_flag music_on   (room 1)
talk bouncer                 a choice gated by requires_flag music_on
  "I fixed your amp."                       →  sets_flag on_the_list
use turntable                requires_flag on_the_list  →  wins: true  (room 2)

Each step is one field on an object or dialogue choice — no code anywhere:

Mechanic	Where to look
A takeable item	fuse in rooms/room0.json
An item lock (needs)	amp in rooms/room1.json
An object setting a flag (sets_flag)	same amp
A hidden dialogue choice (requires_flag)	the bouncer's second choice — try talking to it before and after fixing the amp
Dialogue setting a flag	same choice (sets_flag: on_the_list)
A flag-locked finale (requires_flag + wins)	turntable in rooms/room2.json
Rooms linked by edges (exits)	every room: [N, E, S, W] room numbers
Painted look + walkability (strokes)	every room: Rects with meaning Floor/Wall/None
Per-room music moods	"music": 2/3/4 (eerie street → tense door → jolly club)
Manifest (name, intro, extra verb synonyms)	game.json — try typing fix amp

Dropping lore into a RUNNING game

Rooms can be added live over any control surface — this is the "drop JSON lore in" workflow. lost-fuse/expansion/roof.jsonl adds a roof afterparty above the club:

target/debug/mrpgi-headless --script games/lost-fuse/expansion/roof.jsonl --game games/lost-fuse

It upserts room 3 (validated: a room with no walkable spawn, or exits pointing at rooms that don't exist, is rejected with an error event), then wires room 2's north exit to it. The same two commands work over HTTP (POST /rooms/3, POST /command) or MCP (mrpgi_upsert_room) against a live session.

Asking an LLM for lore

The formats are plain serde types, so generated JSON either loads or fails loudly. A prompt that works well:

Here is a room from my MRPGI game: (paste a room JSON). Write a new room in exactly this format: (describe the room, its objects, its puzzle role, which exits connect where). Rooms are 160×168; sprites available: altar, barrel, chest, key, orc, sign, villager. Only use requires_flag/sets_flag names that exist in my game.

Or skip the copy-paste entirely: register the MCP server (claude mcp add mrpgi -- mrpgi-headless --mcp --game games/lost-fuse) and the model can upsert rooms, render frames to see them, and playtest its own puzzle chain. Full command reference: ../docs/CONTROL.md.

Make your own

mkdir -p games/mygame
cargo run -p mrpgi-core --bin mrpgi-headless -- --sample --game games/mygame  # a starting skeleton
cargo run -p mrpgi -- --game games/mygame                                     # paint it in the editor

Sprites: drop PNGs in games/mygame/sprites/ (auto-quantized to EGA, alpha = transparent, bottom edge = feet). Audio: drop files in sfx/ / music/ to replace the chiptune synth (see MANUAL.md §13). Everything else is the JSON you just read.