RPG World — walk a tile map, talk, open, fight

RPG World turns a game into a tile-map RPG in the spirit of classic 2D role-playing games: you walk a grid map with the keyboard, talk to people, open chests, step through doors and fight monsters, then come back to the same spot. A map is an ordinary scene of the game, so the dialog box, scenarios, saving, music and time of day all work on maps as they do in a visual novel.

It powers the village, forest and desert of RPG Plus. The maps and people themselves come from content mods such as RPG Demo; this mod supplies the rules.

How to play on a map

Walk with WASD or the arrow keys; hold Shift to run.
Act with E or F: talk to the person you face, open the chest, read the sign.
Step onto a doorway or a map edge to go to the next map.
Random battles can start as you walk in some places, such as the forest.
After a battle you are back on the same cell of the same map.
The game saves where you stand; loading puts you back there.

The cell you can act on is framed, and the hint at the bottom left changes to E / F · Interact.

Example: a chest that stays open

The chest in the elder's house is two events on the same cell. The closed one shows while the story flag rpg_house_chest is not set; its scenario gives three coins and sets the flag. From then on the open chest shows instead.

{ "Id": "chest", "X": 9, "Y": 7, "Tile": 14,
  "Scenario": "rpg_demo/events/house_chest",
  "Condition": "rpg_house_chest != 1" },
{ "Id": "chest_open", "X": 9, "Y": 7, "Tile": 15,
  "Scenario": "rpg_demo/events/chest_empty",
  "Condition": "rpg_house_chest == 1" }

ptext "In the chest: old socks and a note saying 'Don't touch'. Too late. Under the socks: three coins." key=rpg_demo/chest/house
action item.add id=money/coin count=3
flag rpg_house_chest 1
end

For authors: maps

A map is a JSON file in a mod's maps/ folder, plus a scene with the same name in scenes/ for its background in battles and its ambience.

Three drawn layers, each a list of rows of tile numbers (. for empty): Back — ground, floors, water; Main — objects at the characters' level: walls, trunks, fences; Front — drawn over the characters: tree crowns, eaves, arches.
Collision — a row layer that overrides the tiles' own passability where needed: an invisible wall at a cliff edge or a gap in a hedge.
Tileset — the tile atlas and the properties of its tiles (solid or not, surfaces, objects).
Spawn — where a new arrival appears; Zoom; optional Ambient colour for interiors (otherwise the time of day lights the map) and Atmosphere (woodland adds leaves, fireflies and water ripples).
Encounters — random battles: on average one per Steps steps, against one of the Groups.

"Encounters": { "Steps": 48, "Groups": ["rpg_slime", "rpg_slime,rpg_slime"] }

For authors: events

Events live in map_events/<map id>/*.json of any mod. An event has a look and an effect, chosen independently:

look: a character Sprite, a single atlas Tile, an item Icon lying on the ground, or nothing (an invisible trigger);
effect: a Teleport to a cell of this or another map, or a Scenario followed by optional inline Commands — the full scenario language, including action rpg.battle, flags and quests;
Trigger: Action (E/F while facing it) or Touch (stepping onto it);
Solid: whether it blocks the way (by default, drawn events do);
Condition: hide the event unless the condition holds;
Pages: alternative looks and effects, each with its own condition — the last page whose condition holds is used;
Route: autonomous movement such as {"Steps": ["left", "wait", "right"], "Every": 0.8} with up/down/left/right, random, toward/away (from the player), wait and face_…;
Light: a glow around the event, {"Radius": 3, "Color": "#ffd8a0"}, seen at dusk and night.

Add to or change another mod's map. Event files are merged in load order: a new Id adds an event to that map, and the same Id from a mod that depends on the owner replaces it. This is how RPG Plus gives the demo's elder new dialogs.

Scenario actions

action rpg.battle enemies=rpg_wolf,rpg_slime win_flag=rpg_wolf_dead
action rpg.teleport map=rpg_forest x=1 y=8 dir=right

rpg.battle starts a battle with the game's battle core and returns to the same cell; on victory win_flag is set to 1, so a map monster whose condition tests that flag disappears. End the scenario after it.
rpg.teleport moves the player to a cell, on this map or another one.

Game settings

Appearance (rpg.player_charset) — the hero's sprite on maps, chosen from the charsets in the game.
Map projection (tile.renderer) — top-down or isometric; see Tile Rendering.

If something goes wrong

A person or chest does not react. Face it and press E or F; a Touch event reacts only when you step on it.
A monster or chest comes back. Its Condition must test the flag that its scenario or win_flag sets.
You cannot walk somewhere that looks open. A solid tile or the map's collision layer blocks that cell.
No battle background. The map's scene in scenes/<map>.json needs a defaultBackground.

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